Snowpack
Snowpack
- Snowpack forms from layers of snow that accumulate in geographic regions and high elevations where the climate includes cold weather for long periods of the year.
Snow accumulations are an essential water resource that feeds streams and rivers when they melt. As a result, the snowpack is both the source of drinking water for many communities and a potential source of flooding.
Snow accumulations also contribute to the mass of glaciers in their area of accumulation. - Assessing the formation and stability of snowpacks is vital in studying and forecasting avalanches.
Scientists study the physical properties of snow under different conditions and their evolution, focusing on snow metamorphism, snow hydrology, the growth of snow cover with climate change, and its effect on ice feedback -albedo and hydrology, both on the ground and using remote sensing.
Snow is also studied in a more global context of impact on animal habitats and plant succession. Significant effort is devoted to the classification of snow, both as a hydrometeor and on the ground.
Climate Change Indicators: Snowpack
Figure 1. Trends in April Snowpack in the Western United States, 1955-2022
Data source: USDA Natural Resources Conservation Service, 2022
Web update: July 2022
Units: degrees; degrees; percent change
This map shows trends in April snowpack in the western United States, measured as snow water equivalent. Blue circles represent increased snow cover; red circles represent a decrease.
This map shows trends during the year snowpack reaches its maximum in the western United States. Blue triangles represent a shift to later timing; red triangles represent a shift to earlier timing.
State | Latitude | Longitude | Timing total change (days) |
AZ | 33.65352 | -109.309 | -26.9671 |
AZ | 33.92123 | -109.459 | -12.5049 |
CA | 38.608 | -119.924 | -2.85 |
CA | 41.58233 | -120.303 | -20.5976 |
CA | 41.99127 | -120.18 | -1.08293 |
CA | 38.5497 | -119.805 | -7.32439 |
CA | 38.849 | -120.08 | -1.13049 |
CA | 38.93403 | -120.055 | 12.5122 |
CA | 38.8519 | -119.937 | -22.2951 |
CA | 38.92431 | -119.916 | -1.21098 |
CA | 39.45269 | -120.294 | -11.4293 |
CA | 39.49001 | -120.282 | -17.0707 |
CA | 39.42752 | -120.313 | -0.87073 |
CA | 38.30367 | -119.551 | -2.86098 |
CA | 38.43745 | -119.366 | -8.72195 |
CA | 38.50576 | -119.626 | 8.904878 |
CA | 38.99927 | -120.131 | -7.56951 |
CA | 38.31021 | -119.6 | -0.34024 |
CA | 39.18986 | -120.266 | -1.40122 |
CA | 39.17162 | -120.154 | -19.7854 |
CA | 39.30087 | -120.184 | 0.534146 |
CA | 38.07298 | -119.234 | -0.33659 |
CA | 39.13545 | -120.219 | -2.06707 |
CO | 37.33067 | -105.068 | -33.0988 |
CO | 40.31176 | -105.647 | -9.76098 |
CO | 39.80364 | -105.778 | -6.16829 |
CO | 39.08758 | -106.542 | -12.4866 |
CO | 39.87504 | -107.599 | -24.4244 |
CO | 38.89435 | -106.953 | -13.7744 |
CO | 37.65083 | -107.806 | -8.35976 |
CO | 40.39591 | -106.604 | -19.5329 |
CO | 39.48917 | -106.172 | -10.3098 |
CO | 37.20939 | -105.2 | -5.50976 |
CO | 37.01877 | -106.453 | -11.3598 |
CO | 40.80572 | -105.77 | -0.95488 |
CO | 40.5337 | -106.781 | -14.6012 |
CO | 40.84758 | -106.969 | -16.2768 |
CO | 39.38014 | -106.198 | -6.21951 |
CO | 39.64646 | -105.869 | -7.30244 |
CO | 39.36092 | -106.06 | 0.636585 |
CO | 37.93389 | -107.676 | -7.77073 |
CO | 39.07543 | -106.612 | -10.9244 |
CO | 40.53285 | -105.887 | -6.88537 |
CO | 39.3172 | -106.615 | -13.3573 |
CO | 39.93659 | -105.59 | -12.6585 |
CO | 40.41446 | -105.819 | -13.4963 |
CO | 37.38028 | -106.548 | -39.5707 |
CO | 37.79895 | -107.925 | -28.35 |
CO | 37.89169 | -108.196 | -3.87073 |
CO | 39.12899 | -107.288 | -23.8207 |
CO | 37.61779 | -107.039 | -20.389 |
CO | 37.84737 | -107.727 | -15.8854 |
CO | 40.03581 | -105.545 | 3.72439 |
CO | 38.81982 | -106.59 | 5.341463 |
CO | 39.04433 | -107.88 | -6.65488 |
CO | 40.39803 | -105.846 | -12.4098 |
CO | 38.48864 | -106.34 | -11.8134 |
CO | 37.89168 | -107.714 | -5.34146 |
CO | 40.87498 | -106.047 | -6.37683 |
CO | 37.99076 | -107.204 | -14.5024 |
CO | 40.5374 | -106.677 | -3.69146 |
CO | 40.03307 | -105.576 | 6.307317 |
CO | 37.48563 | -106.835 | -19.3683 |
CO | 39.61765 | -106.38 | -30.5268 |
CO | 37.21423 | -105.123 | -18.6037 |
CO | 40.34734 | -106.095 | -7.08659 |
CO | 40.43397 | -105.736 | 1.243902 |
ID | 44.30342 | -115.234 | -6.92561 |
ID | 44.60533 | -116.981 | -4.82561 |
ID | 44.62621 | -115.796 | -7.92439 |
ID | 42.16442 | -114.193 | -12.1098 |
ID | 44.28846 | -115.655 | -1.76341 |
ID | 44.437 | -111.994 | -17.8024 |
ID | 43.6025 | -114.674 | -20.9415 |
ID | 42.0505 | -111.601 | -10.4159 |
ID | 43.6104 | -113.931 | -8.55 |
ID | 43.9538 | -115.274 | -13.7195 |
ID | 42.32029 | -113.616 | -8.21341 |
ID | 43.71077 | -114.159 | -0.2122 |
ID | 42.18072 | -114.287 | -4.00976 |
ID | 44.4147 | -113.398 | -17.0488 |
ID | 44.84237 | -114.269 | -21.3293 |
ID | 45.69694 | -115.23 | -10.0061 |
ID | 45.18848 | -115.972 | -8.48049 |
ID | 42.56248 | -111.298 | -6.8122 |
ID | 42.95275 | -111.359 | -6.73537 |
ID | 42.76478 | -116.9 | -14.3159 |
ID | 43.86117 | -114.209 | -6.89268 |
ID | 43.626 | -113.969 | -4.89878 |
ID | 43.62903 | -115.438 | -9.30732 |
MT | 48.5712 | -115.446 | 1.723171 |
MT | 46.09713 | -113.13 | -0.39512 |
MT | 45.79737 | -112.52 | -15.2159 |
MT | 44.47147 | -112.982 | -6.70976 |
MT | 44.94966 | -111.359 | -4.02805 |
MT | 44.50832 | -111.128 | 4.507317 |
MT | 46.414 | -113.431 | -8.75854 |
MT | 45.16507 | -113.501 | -3.45366 |
MT | 46.5596 | -111.29 | -1.92073 |
MT | 45.2719 | -110.249 | -11.2756 |
MT | 45.8838 | -113.326 | -13.4268 |
MT | 44.96192 | -111.294 | -13.2951 |
MT | 45.01788 | -111.846 | -2.10732 |
MT | 45.19405 | -109.345 | 5.941463 |
MT | 46.46523 | -113.394 | -9.02927 |
MT | 47.05678 | -112.595 | -26.5939 |
MT | 47.08158 | -112.73 | 0.764634 |
MT | 46.78942 | -109.512 | 11.95244 |
MT | 46.18367 | -113.853 | -9.79024 |
MT | 45.17367 | -113.584 | -0.63659 |
MT | 46.79279 | -110.675 | -4.93171 |
MT | 44.79317 | -112.056 | -5.98902 |
MT | 48.43412 | -113.937 | -7.62073 |
MT | 45.06235 | -109.945 | 5.359756 |
MT | 48.80225 | -113.857 | 7.412195 |
MT | 46.43545 | -112.193 | -12.739 |
MT | 48.91453 | -114.767 | 9.834146 |
MT | 48.30754 | -114.841 | -19.1195 |
MT | 48.9723 | -115.953 | -10.7378 |
MT | 46.9751 | -115.035 | 6.958537 |
MT | 47.42749 | -113.775 | 3.358537 |
MT | 44.58907 | -111.825 | -15.8305 |
MT | 44.9938 | -113.444 | -7.44878 |
MT | 45.5041 | -110.966 | 14.07073 |
MT | 45.50871 | -111.923 | -2.74024 |
MT | 46.88293 | -113.322 | -2.22805 |
MT | 44.58623 | -111.116 | 5.85 |
MT | 48.79698 | -113.671 | 2.436585 |
MT | 45.21759 | -110.237 | -11.8024 |
MT | 47.91727 | -112.824 | -3.77195 |
MT | 45.40957 | -112.959 | -2.34878 |
MT | 46.8716 | -113.277 | 4.639024 |
MT | 45.73107 | -114.481 | -7.17805 |
MT | 48.15678 | -113.946 | -2.29756 |
MT | 45.00565 | -110.014 | -11.3159 |
MT | 46.57978 | -111.268 | 6.592683 |
MT | 48.30305 | -113.329 | -33.6622 |
MT | 45.41905 | -110.088 | -5.11463 |
MT | 46.11192 | -110.47 | -8.08171 |
MT | 46.35613 | -112.262 | -8.87927 |
MT | 46.0896 | -110.434 | 1.141463 |
MT | 45.69259 | -113.968 | 2.7 |
MT | 45.40125 | -110.958 | 0.047561 |
MT | 46.24212 | -113.773 | -17.7768 |
MT | 46.77962 | -110.622 | -3.59634 |
MT | 48.90902 | -114.863 | -6.84512 |
MT | 44.78562 | -111.71 | -10.4049 |
MT | 46.14287 | -114.448 | -3.37683 |
MT | 46.1438 | -114.506 | -8.98537 |
MT | 47.91998 | -112.791 | 7.990244 |
MT | 46.27368 | -113.164 | -1.6939 |
MT | 44.61088 | -111.15 | -8.41098 |
MT | 45.04575 | -109.91 | -3.46829 |
MT | 47.44847 | -112.814 | -11.261 |
MT | 48.97523 | -115.819 | 11.10366 |
MT | 44.65866 | -111.092 | -5.19878 |
MT | 46.12588 | -113.308 | -8.70732 |
NM | 36.51174 | -106.315 | -21.2341 |
NM | 36.95606 | -106.657 | -20.9159 |
NM | 36.19418 | -105.557 | -25.9134 |
NM | 36.71632 | -106.264 | -9.73902 |
NM | 36.99396 | -105.26 | -28.4817 |
NM | 35.92195 | -106.392 | -29.6159 |
NM | 36.69935 | -105.341 | -22.4195 |
NM | 36.00152 | -106.834 | -20.3415 |
NM | 33.3696 | -108.707 | -13.672 |
NV | 41.83384 | -115.453 | -9.62195 |
NV | 39.31917 | -114.623 | -4.36098 |
NV | 41.76168 | -115.693 | -11.2829 |
NV | 39.29148 | -117.115 | -3.8122 |
NV | 41.75067 | -117.532 | -4.68293 |
NV | 40.27551 | -115.54 | -15.9183 |
NV | 40.89343 | -115.211 | -7.83293 |
NV | 41.82098 | -116.102 | -13.3463 |
NV | 41.67032 | -117.567 | -10.8695 |
NV | 40.3848 | -115.528 | -7.17439 |
NV | 41.54675 | -116.005 | -11.4329 |
NV | 40.6448 | -115.381 | -8.38902 |
NV | 41.77637 | -116.03 | -7.1561 |
NV | 39.16395 | -119.897 | -5.20976 |
NV | 39.31573 | -119.895 | -6.03659 |
NV | 41.87255 | -115.247 | -2.28293 |
NV | 41.73732 | -115.472 | -4.47805 |
NV | 39.13242 | -114.956 | -7.69756 |
OR | 45.19085 | -119.254 | -2.67439 |
OR | 45.14532 | -118.219 | 14.09268 |
OR | 42.05257 | -122.855 | 4.796341 |
OR | 42.40717 | -122.266 | -3.81585 |
OR | 45.4287 | -121.856 | -1.44878 |
OR | 44.24767 | -118.517 | -11.9488 |
OR | 44.83052 | -118.188 | -23.5646 |
OR | 45.36428 | -118.467 | -11.3232 |
OR | 43.59042 | -122.06 | -5.51341 |
OR | 43.22625 | -121.807 | -4.06098 |
OR | 42.53305 | -122.177 | -7.29512 |
OR | 44.4465 | -119.93 | -14.5573 |
OR | 44.86887 | -118.114 | -17.1695 |
OR | 42.70992 | -118.632 | -10.3939 |
OR | 42.3801 | -122.349 | 17.6561 |
OR | 42.43933 | -122.229 | -12.4537 |
OR | 44.7638 | -118.312 | 0.845122 |
OR | 45.69682 | -118.107 | 15.03293 |
OR | 44.42042 | -121.857 | -30.7793 |
OR | 43.66917 | -122.569 | -6.29268 |
OR | 43.80368 | -121.948 | -9.43171 |
OR | 44.21007 | -118.638 | -22.9207 |
OR | 44.2103 | -121.873 | -14.7915 |
OR | 45.27173 | -117.687 | 6.245122 |
OR | 45.32097 | -121.716 | -6.20854 |
OR | 45.26522 | -117.174 | -6.29268 |
OR | 44.42917 | -120.331 | -21.5305 |
OR | 45.4643 | -121.704 | 12.02195 |
OR | 43.90098 | -122.031 | -5.53171 |
OR | 43.61193 | -122.118 | 3.420732 |
OR | 42.69825 | -122.142 | -6.22317 |
OR | 42.95615 | -121.181 | -8.08537 |
OR | 42.75333 | -118.688 | -13.7561 |
OR | 43.94885 | -119.54 | -6.42439 |
OR | 44.26423 | -119.022 | 3.131707 |
OR | 42.6957 | -120.802 | -16.2073 |
OR | 43.44907 | -122.138 | -1.13049 |
OR | 45.07707 | -117.551 | -8.21707 |
OR | 44.14425 | -121.641 | -23.2756 |
OR | 44.65567 | -118.426 | -3.47195 |
OR | 45.06703 | -118.152 | -8.91951 |
UT | 39.13683 | -111.558 | -18.3146 |
UT | 40.61233 | -111.098 | 5.330488 |
UT | 41.37603 | -111.944 | -18.0402 |
UT | 41.38291 | -111.921 | -22.8329 |
UT | 38.30183 | -112.357 | 2.579268 |
UT | 38.6799 | -111.598 | -12.4317 |
UT | 38.50809 | -112.019 | -22.2 |
UT | 40.58102 | -110.586 | -9.6439 |
UT | 39.134 | -111.437 | -16.6793 |
UT | 41.68541 | -111.42 | -8.82073 |
UT | 37.66098 | -112.741 | -7.02805 |
UT | 40.85464 | -111.048 | -12.8671 |
UT | 40.88529 | -111.07 | -0.54512 |
UT | 40.77458 | -110.011 | -17.6195 |
UT | 39.86671 | -111.284 | -17.7915 |
UT | 39.89275 | -111.252 | -6.64024 |
UT | 40.35747 | -111.09 | -21.1171 |
UT | 40.2953 | -111.257 | -8.45488 |
UT | 39.04554 | -111.469 | -10.1159 |
UT | 41.41289 | -111.538 | -10.8183 |
UT | 40.97462 | -111.81 | -7.97195 |
UT | 38.77246 | -111.677 | -8.66707 |
UT | 40.71785 | -110.467 | -13.6463 |
UT | 38.80034 | -111.683 | -19.972 |
UT | 37.48997 | -112.576 | -4.34268 |
UT | 40.79669 | -110.885 | -17.2427 |
UT | 41.31372 | -111.446 | -9.91829 |
UT | 39.89166 | -110.746 | -18.4829 |
UT | 38.48383 | -112.393 | -19.9939 |
UT | 40.71632 | -109.544 | -15.2268 |
UT | 37.52664 | -113.054 | -14.978 |
UT | 40.59709 | -110.433 | -10.789 |
UT | 38.48226 | -109.272 | -16.5439 |
UT | 40.86493 | -110.798 | -18.2854 |
UT | 41.40562 | -111.826 | -15.2085 |
UT | 37.51255 | -113.397 | -10.778 |
UT | 39.68338 | -111.318 | -21.8159 |
UT | 38.30285 | -112.436 | -4.08293 |
UT | 37.56933 | -112.838 | -5.63415 |
UT | 41.46547 | -111.497 | -12.8963 |
UT | 40.60798 | -109.888 | -18.5159 |
UT | 40.76184 | -111.629 | 2.209756 |
UT | 39.92976 | -111.631 | -19.9573 |
UT | 39.01219 | -111.583 | -21.4866 |
UT | 39.45197 | -111.272 | -13.65 |
UT | 40.54875 | -110.693 | -0.69146 |
UT | 40.44293 | -112.224 | -9.02195 |
UT | 39.31042 | -111.433 | -19.4488 |
UT | 40.78931 | -111.092 | -2.06707 |
UT | 40.90862 | -110.505 | -7.6061 |
UT | 40.16483 | -111.207 | -4.92805 |
UT | 40.42817 | -111.616 | -8.38902 |
UT | 41.89833 | -111.63 | -12.0146 |
UT | 40.678 | -110.949 | 3.237805 |
UT | 40.739 | -109.673 | -12.278 |
UT | 39.93667 | -112.415 | -10.9317 |
UT | 37.575 | -112.902 | -8.13293 |
UT | 37.83633 | -111.882 | -13.9683 |
WA | 47.35037 | -120.68 | -30.2817 |
WA | 46.27143 | -121.963 | -6.73902 |
WA | 48.44488 | -120.916 | 0.940244 |
WA | 46.62153 | -121.386 | -0.70244 |
WA | 47.9909 | -120.566 | 0.493902 |
WA | 47.74607 | -121.093 | 1.309756 |
WA | 46.09497 | -121.763 | -5.77683 |
WA | 47.23328 | -120.294 | 18.48659 |
WA | 47.28734 | -120.37 | -5.8061 |
WA | 46.64142 | -121.382 | 2.930488 |
WY | 44.8007 | -107.844 | -0.17561 |
WY | 43.88743 | -107.061 | -3.02927 |
WY | 44.94307 | -109.567 | 5.831707 |
WY | 44.37667 | -109.793 | -0.90732 |
WY | 44.67888 | -107.581 | 3.731707 |
WY | 44.71961 | -110.511 | 9.534146 |
WY | 44.40343 | -107.061 | -0.99146 |
WY | 41.30399 | -107.153 | -6.98415 |
WY | 44.57462 | -107.295 | 0.153659 |
WY | 43.00657 | -109.759 | -3.80488 |
WY | 44.12612 | -110.834 | -1.52195 |
WY | 43.38939 | -110.129 | -10.8402 |
WY | 44.25602 | -106.98 | 1.821951 |
WY | 42.86984 | -109.095 | 3.585366 |
WY | 43.86067 | -109.322 | -3.62561 |
WY | 44.20862 | -110.666 | -0.36951 |
WY | 43.50278 | -109.752 | -7.18902 |
WY | 43.17387 | -110.14 | -7.1378 |
WY | 43.62728 | -107.181 | -11.2646 |
WY | 41.33087 | -106.376 | -8.65244 |
WY | 41.15397 | -106.969 | 4.218293 |
WY | 43.65868 | -109.01 | -6.30732 |
WY | 44.73396 | -109.915 | -8.84634 |
WY | 43.51687 | -110.913 | -14.4366 |
WY | 44.16188 | -107.126 | -6.16829 |
WY | 42.5075 | -110.91 | -2.21341 |
WY | 44.50012 | -107.429 | -0.6878 |
WY | 41.3295 | -106.503 | -15.0915 |
WY | 44.7225 | -107.4 | 0.12439 |
WY | 44.47764 | -110.157 | -20.6451 |
WY | 43.74902 | -110.058 | -8.43293 |
WY | 42.69525 | -108.896 | -0.95488 |
WY | 44.15178 | -110.221 | -6.69878 |
WY | 41.1591 | -106.928 | -12.4537 |
WY | 44.80417 | -109.657 | -9.69878 |
Figure 2. Change in Peak Snowpack Timing in the Western United States, 1982-2021
Data source: USDA Natural Resources Conservation Service, 2022
Web update: July 2022
Units: degrees; degrees; days
This graph shows trends during the year snowpack reaches its maximum in the western United States. The line in this graph represents the average of all the locations shown in Figure 2.
Water year | Peak date |
1982 | 198.8963 |
1983 | 209.4482 |
1984 | 204.3232 |
1985 | 187.8689 |
1986 | 185.9451 |
1987 | 186.5854 |
1988 | 187.2378 |
1989 | 183.2409 |
1990 | 185.8079 |
1991 | 199.5732 |
1992 | 176.9451 |
1993 | 194.0793 |
1994 | 185.9299 |
1995 | 199.6829 |
1996 | 192.6402 |
1997 | 189.9451 |
1998 | 195.0427 |
1999 | 199.5579 |
2000 | 184.0366 |
2001 | 191.0244 |
2002 | 186.1433 |
2003 | 194.2652 |
2004 | 174.75 |
2005 | 193.6433 |
2006 | 191.7896 |
2007 | 177.6524 |
2008 | 197.5091 |
2009 | 196.375 |
2010 | 199 |
2011 | 206.5305 |
2012 | 181.7073 |
2013 | 186.6311 |
2014 | 187.5427 |
2015 | 164.1616 |
2016 | 182.061 |
2017 | 184.1433 |
2018 | 188.4512 |
2019 | 191.5915 |
2020 | 190.314 |
2021 | 185.7073 |
Figure 3. Average Date of Peak Snowpack in the Western United States, 1982-2021
Data source: USDA Natural Resources Conservation Service, 2022
Web update: July 2022
Units: day of water year
This map shows trends in the length of the western United States snowpack season in days. Blue circles show where the season has extended; red circles indicate where it has shortened.
State | Latitude | Longitude | Duration total change (days) |
CO | 37.33 | -105.07 | -25.372 |
OR | 45.19 | -119.25 | -21.1427 |
AZ | 34.46 | -111.41 | -37.9793 |
WY | 44.8 | -107.84 | -7.85122 |
AZ | 33.98 | -109.5 | -74.3927 |
MT | 48.57 | -115.45 | -16.1854 |
ID | 44.3 | -115.23 | -20.25 |
MT | 46.1 | -113.13 | 6.329268 |
MT | 45.8 | -112.52 | -19.0024 |
NM | 36.51 | -106.32 | -32.6963 |
MT | 44.47 | -112.98 | 8.147561 |
NV | 41.83 | -115.45 | -21.9037 |
CO | 40.31 | -105.65 | -2.95976 |
WY | 43.89 | -107.06 | 4.917073 |
WY | 44.94 | -109.57 | 12.16463 |
MT | 44.95 | -111.36 | -9.5378 |
UT | 39.14 | -111.56 | -35.0963 |
UT | 40.61 | -111.1 | -2.56829 |
OR | 45.15 | -118.22 | -7.27895 |
UT | 41.38 | -111.94 | -33.0951 |
UT | 41.38 | -111.92 | -26.2134 |
NV | 39.32 | -114.62 | -19.4085 |
CO | 39.8 | -105.78 | -3.91098 |
NV | 41.76 | -115.69 | 1.62439 |
NV | 39.29 | -117.12 | -17.1915 |
ID | 44.63 | -115.8 | -21.3512 |
UT | 38.3 | -112.36 | -33.0526 |
OR | 42.05 | -122.85 | -12.1098 |
OR | 42.41 | -122.27 | -28.4598 |
MT | 44.51 | -111.13 | 4.093902 |
UT | 38.68 | -111.6 | -22.3756 |
MT | 46.41 | -113.43 | -18.3329 |
WY | 44.38 | -109.79 | 3.373171 |
OR | 45.43 | -121.86 | -32.8354 |
WA | 47.35 | -120.68 | -43.9061 |
WY | 42.96 | -110.61 | 10.13415 |
MT | 45.17 | -113.5 | -3.61463 |
CA | 38.61 | -119.92 | -41.3963 |
OR | 44.25 | -118.52 | -17.46 |
WY | 44.68 | -107.58 | -4.57683 |
ID | 42.16 | -114.19 | -8.5061 |
MT | 46.56 | -111.29 | 11.24268 |
OR | 44.83 | -118.19 | -17.561 |
OR | 45.36 | -118.47 | -18.128 |
MT | 45.27 | -110.25 | -11.0634 |
UT | 38.51 | -112.02 | -32.5683 |
UT | 40.58 | -110.59 | -28.1049 |
CO | 39.09 | -106.54 | 3.365854 |
UT | 39.13 | -111.44 | -45.3256 |
NV | 41.75 | -117.53 | -9.15 |
UT | 41.69 | -111.42 | -13.9244 |
CO | 39.88 | -107.6 | -14.8902 |
CO | 38.89 | -106.95 | -12.7463 |
MT | 45.88 | -113.33 | -22.8512 |
WY | 44.72 | -110.51 | -5.20864 |
MT | 44.96 | -111.29 | -1.17805 |
CO | 37.65 | -107.81 | -26.9927 |
OR | 43.59 | -122.06 | -13.8915 |
UT | 37.66 | -112.74 | -33.161 |
CA | 41.58 | -120.3 | -26.9341 |
UT | 40.85 | -111.05 | -29.5244 |
UT | 40.89 | -111.07 | -2.37439 |
NM | 36.96 | -106.66 | -8.04878 |
OR | 43.23 | -121.81 | -41.0927 |
UT | 40.77 | -110.01 | -15.0366 |
OR | 45.1 | -121.75 | -12.7939 |
UT | 39.87 | -111.28 | -28.3793 |
UT | 39.89 | -111.25 | -24.2524 |
OR | 45.19 | -121.69 | -37.1488 |
WY | 44.4 | -107.06 | -2.36341 |
MT | 45.02 | -111.85 | 1.335366 |
OR | 42.53 | -122.18 | -28.3317 |
MT | 45.19 | -109.35 | -7.0061 |
CO | 40.4 | -106.6 | -11.8134 |
MT | 46.47 | -113.39 | -15.8561 |
MT | 47.06 | -112.6 | -63.3256 |
MT | 47.08 | -112.73 | -0.6 |
CO | 39.49 | -106.17 | 4.039024 |
AZ | 33.8 | -109.15 | -51 |
NV | 40.28 | -115.54 | -20.2134 |
WA | 47.28 | -121.67 | -54.9512 |
OR | 45.19 | -118.55 | -45.3079 |
ID | 44.29 | -115.66 | -21.5305 |
ID | 44.44 | -111.99 | -13.8402 |
MT | 46.79 | -109.51 | 14.06341 |
CO | 37.21 | -105.2 | 6.753659 |
CO | 37.02 | -106.45 | -9.8378 |
UT | 40.36 | -111.09 | -31.4561 |
MT | 46.18 | -113.85 | -6.27439 |
OR | 44.52 | -122.09 | -55.6939 |
UT | 40.3 | -111.26 | -19.3902 |
MT | 45.17 | -113.58 | 12.71707 |
MT | 46.79 | -110.68 | 0.808537 |
CO | 40.81 | -105.77 | -4.5878 |
OR | 44.45 | -119.93 | -19.2 |
UT | 39.05 | -111.47 | -20.7711 |
NV | 41.97 | -118.19 | -61.2915 |
CA | 41.99 | -120.18 | -6.99512 |
MT | 44.79 | -112.06 | -11.1402 |
WY | 41.3 | -107.15 | -20.9854 |
ID | 43.6 | -114.67 | -19.178 |
WY | 44.57 | -107.3 | -7.50366 |
NV | 40.89 | -115.21 | -7.4122 |
UT | 41.41 | -111.54 | -15.3329 |
CO | 40.53 | -106.78 | 4.32439 |
CA | 38.55 | -119.8 | -40.7561 |
CA | 38.85 | -120.08 | -22.3866 |
OR | 44.87 | -118.11 | -26.6817 |
CO | 40.85 | -106.97 | -4.13684 |
WY | 43.01 | -109.76 | -3.48293 |
MT | 48.43 | -113.94 | -16.8805 |
OR | 45.56 | -118.45 | -31.4415 |
CA | 38.93 | -120.05 | -20.4037 |
UT | 40.97 | -111.81 | -13.7744 |
UT | 38.77 | -111.68 | -17.122 |
NV | 41.82 | -116.1 | -29.1329 |
OR | 42.71 | -118.63 | -22.7085 |
OR | 42.38 | -122.35 | -15.45 |
MT | 45.06 | -109.94 | 3.42439 |
UT | 40.72 | -110.47 | -18.3549 |
MT | 48.8 | -113.86 | 5.813415 |
OR | 42.44 | -122.23 | -25.7305 |
ID | 42.05 | -111.6 | -14.9598 |
CO | 39.38 | -106.2 | -4.37927 |
NM | 33.74 | -108.94 | -36.3366 |
MT | 46.44 | -112.19 | -22.7963 |
AZ | 35.07 | -111.84 | -8.0378 |
NM | 36.19 | -105.56 | -35.2974 |
ID | 43.61 | -113.93 | -9.39512 |
OR | 44.76 | -118.31 | -1.68659 |
UT | 38.8 | -111.68 | -19.8255 |
NV | 41.67 | -117.57 | -30.9037 |
WY | 44.13 | -110.83 | -10.7524 |
MT | 48.91 | -114.77 | -2.85366 |
NV | 40.38 | -115.53 | -16.2402 |
OR | 45.62 | -121.7 | -28.8439 |
CO | 39.65 | -105.87 | 1.792683 |
WY | 43.39 | -110.13 | -5.84634 |
CA | 38.85 | -119.94 | -8.53171 |
MT | 48.31 | -114.84 | -29.6085 |
AZ | 33.65 | -109.31 | -50.3012 |
WY | 44.26 | -106.98 | -2.06341 |
UT | 37.49 | -112.58 | -34.5832 |
MT | 48.97 | -115.95 | -14.572 |
UT | 40.8 | -110.88 | -26.9854 |
CA | 38.92 | -119.92 | -28.65 |
OR | 45.7 | -118.11 | 8.652439 |
WY | 42.87 | -109.09 | -4.8 |
OR | 44.42 | -121.86 | -75.7866 |
OR | 43.67 | -122.57 | -57.3474 |
MT | 46.98 | -115.03 | 0.164634 |
CO | 39.36 | -106.06 | 3.391463 |
NM | 36.72 | -106.26 | -19.7012 |
UT | 41.31 | -111.45 | -12.8085 |
CO | 37.93 | -107.68 | -7.75976 |
CA | 39.45 | -120.29 | -43.2366 |
CA | 39.49 | -120.28 | -39.6329 |
CA | 39.43 | -120.31 | -14.3341 |
CO | 39.08 | -106.61 | 2.436585 |
UT | 39.89 | -110.75 | -31.4378 |
OR | 43.8 | -121.95 | -21.0553 |
NV | 41.55 | -116.01 | -20.6451 |
CO | 40.53 | -105.89 | -18.161 |
OR | 44.39 | -122.17 | -63.5049 |
CO | 39.32 | -106.62 | -7.67927 |
UT | 38.48 | -112.39 | -37.5073 |
OR | 42.72 | -123.2 | -9.00732 |
UT | 40.72 | -109.54 | -23.7073 |
WY | 43.86 | -109.32 | -9.79024 |
UT | 37.53 | -113.05 | -23.539 |
MT | 47.43 | -113.78 | -25.9098 |
OR | 44.21 | -118.64 | -20.0605 |
CO | 39.94 | -105.59 | 10.54024 |
CO | 40.41 | -105.82 | -8.43293 |
UT | 40.6 | -110.43 | -12.3805 |
MT | 44.59 | -111.82 | -24.8122 |
NV | 41.52 | -117.63 | -75.2159 |
NV | 40.64 | -115.38 | -26.3012 |
UT | 38.48 | -109.27 | -25.6427 |
NV | 41.78 | -116.03 | -25.189 |
CA | 38.3 | -119.55 | -33.4866 |
MT | 44.99 | -113.44 | -20.6415 |
WY | 44.21 | -110.67 | -16.7524 |
MT | 45.5 | -110.97 | -5.3122 |
UT | 40.86 | -110.8 | -22.628 |
CO | 37.38 | -106.55 | -16.3024 |
UT | 41.41 | -111.83 | -17.4732 |
WY | 43.5 | -109.75 | -0.96585 |
CO | 37.8 | -107.92 | -21.589 |
CA | 38.44 | -119.37 | -41.111 |
CO | 37.89 | -108.2 | -13.9354 |
WA | 46.27 | -121.96 | -17.2885 |
UT | 37.51 | -113.4 | -33.6402 |
NM | 33.36 | -107.83 | -52.3573 |
WY | 43.17 | -110.14 | -7.98293 |
MT | 45.51 | -111.92 | 4.558537 |
MT | 46.88 | -113.32 | -18.6073 |
OR | 45.27 | -118.85 | -31.6902 |
MT | 44.59 | -111.12 | -7.3939 |
ID | 42.18 | -114.29 | -7.41585 |
UT | 39.68 | -111.32 | -25.2293 |
MT | 48.8 | -113.67 | -10.0354 |
OR | 44.59 | -121.97 | -49.2695 |
NV | 39.16 | -119.9 | -14.0598 |
AZ | 33.92 | -109.46 | -64.1159 |
CO | 39.13 | -107.29 | -21.0512 |
OR | 44.21 | -121.87 | -24.7658 |
UT | 38.3 | -112.44 | -15.7939 |
CO | 37.62 | -107.04 | -8.99268 |
WY | 43.63 | -107.18 | -27.4317 |
UT | 37.57 | -112.84 | -32.9243 |
CO | 37.85 | -107.73 | -2.32317 |
UT | 41.47 | -111.5 | -11.3159 |
MT | 45.22 | -110.24 | -5.22805 |
AZ | 34.94 | -111.52 | -51.3585 |
UT | 40.61 | -109.89 | -16.1232 |
OR | 45.27 | -117.69 | 7.664634 |
MT | 47.92 | -112.82 | -4.14146 |
ID | 45.7 | -115.23 | -0.99878 |
OR | 45.32 | -121.72 | -18.2122 |
NV | 39.32 | -119.89 | -26.5024 |
OR | 45.27 | -117.17 | 12.05122 |
MT | 45.41 | -112.96 | 8.165854 |
MT | 46.87 | -113.28 | -7.2878 |
OR | 43.51 | -121.98 | -15.5415 |
MT | 45.73 | -114.48 | -11.7476 |
CO | 40.04 | -105.55 | 10.93171 |
MT | 48.16 | -113.95 | -2.5061 |
NM | 36.99 | -105.26 | -43.4159 |
OR | 45.55 | -122 | 8.937805 |
WY | 41.33 | -106.38 | -10.3829 |
MT | 45.01 | -110.01 | -16.7561 |
OR | 44.43 | -120.33 | -35.5207 |
WY | 41.15 | -106.97 | -0.49756 |
WY | 43.66 | -109.01 | -5.44756 |
CO | 38.82 | -106.59 | 14.30854 |
WA | 48.44 | -120.92 | -20.3598 |
CO | 39.04 | -107.88 | -11.8976 |
WY | 44.73 | -109.91 | -14.528 |
UT | 40.76 | -111.63 | -8.07073 |
UT | 39.93 | -111.63 | -44.7841 |
OR | 45.04 | -121.93 | -47.3211 |
CO | 40.4 | -105.85 | -6.88171 |
WY | 43.52 | -110.91 | 2.392105 |
MT | 46.58 | -111.27 | -0.57073 |
UT | 39.01 | -111.58 | -30.622 |
WA | 46.62 | -121.39 | 8.509756 |
MT | 48.3 | -113.33 | -58.6354 |
MT | 45.42 | -110.09 | -9.46463 |
CA | 38.51 | -119.63 | 2.129268 |
NV | 41.87 | -115.25 | -0.93293 |
WA | 47.99 | -120.57 | -16.5293 |
MT | 46.11 | -110.47 | -22.639 |
CO | 38.49 | -106.34 | -5.08902 |
WY | 44.16 | -107.13 | 1.803659 |
OR | 42.32 | -120.83 | -101.879 |
NM | 35.92 | -106.39 | -60.4207 |
OR | 43.66 | -122.21 | -2.79146 |
OR | 45.46 | -121.7 | -29.8683 |
CO | 37.89 | -107.71 | -1.44878 |
UT | 39.45 | -111.27 | -33.5122 |
NM | 36.7 | -105.34 | -29.5098 |
CO | 40.87 | -106.05 | 5.012195 |
OR | 43.9 | -122.03 | -27.8085 |
UT | 40.55 | -110.69 | -7.3061 |
OR | 44.01 | -118.84 | -17.6524 |
MT | 46.36 | -112.26 | 1.979268 |
UT | 40.44 | -112.22 | -32.1988 |
CA | 39 | -120.13 | -27.439 |
MT | 46.09 | -110.43 | -17.5756 |
OR | 45.54 | -123.37 | -46.1817 |
MT | 45.69 | -113.97 | 5.670732 |
OR | 43.61 | -122.12 | -27.7829 |
WY | 42.51 | -110.91 | -3.62561 |
OR | 44.44 | -121.95 | -42.8963 |
UT | 39.31 | -111.43 | -41.2573 |
OR | 45.53 | -123.3 | -75.611 |
NM | 36 | -106.83 | -39.45 |
OR | 42.7 | -122.14 | -12.5195 |
NV | 41.74 | -115.47 | -28.4671 |
WY | 44.5 | -107.43 | -3.62561 |
MT | 45.4 | -110.96 | 5.381707 |
NM | 32.92 | -108.15 | -82.8711 |
OR | 42.96 | -121.18 | -28.0427 |
MT | 46.24 | -113.77 | -17.7622 |
ID | 42.56 | -111.3 | -13.2805 |
CO | 37.99 | -107.2 | -13.1524 |
UT | 40.79 | -111.09 | -19.2732 |
CA | 38.31 | -119.6 | -22.7305 |
WY | 41.33 | -106.5 | -23.6341 |
ID | 42.76 | -116.9 | -32.3671 |
CA | 38.67 | -119.82 | 3.62561 |
MT | 46.78 | -110.62 | 2.443902 |
CA | 39.19 | -120.27 | -38.0707 |
MT | 48.91 | -114.86 | -0.51585 |
OR | 44.26 | -119.02 | -14.9634 |
UT | 40.91 | -110.5 | -16.6756 |
WA | 47.75 | -121.09 | -10.6317 |
OR | 42.13 | -120.84 | -48.9111 |
UT | 40.16 | -111.21 | -20.1695 |
WY | 44.72 | -107.4 | 2.630488 |
OR | 42.7 | -120.8 | -12.3 |
OR | 43.45 | -122.14 | -9.88256 |
WA | 46.09 | -121.76 | -2.98293 |
ID | 43.63 | -113.97 | -11.9488 |
WY | 44.48 | -110.16 | -15.7756 |
CA | 39.17 | -120.15 | -65.4695 |
OR | 42.69 | -121.43 | -26.3817 |
NV | 41.23 | -116.03 | -35.0671 |
OR | 45.08 | -117.55 | -17.9053 |
MT | 44.79 | -111.71 | -35.9378 |
OR | 44.14 | -121.64 | -38.0783 |
UT | 40.43 | -111.62 | -18.8963 |
OR | 44.66 | -118.43 | -5.59756 |
WY | 43.75 | -110.06 | -0.22317 |
UT | 41.9 | -111.63 | -13.8951 |
CO | 40.54 | -106.68 | -18.9037 |
WY | 42.7 | -108.9 | 2.078049 |
UT | 40.68 | -110.95 | -11.7476 |
WA | 47.23 | -120.29 | 9.6 |
UT | 40.74 | -109.67 | -25.9317 |
CA | 39.3 | -120.18 | -16.5329 |
MT | 46.14 | -114.45 | -1.8622 |
MT | 46.14 | -114.51 | -13.7561 |
WY | 44.15 | -110.22 | -8.96707 |
CO | 40.03 | -105.58 | 4.964634 |
CO | 37.49 | -106.84 | -18.4939 |
WA | 47.29 | -120.37 | -2.01585 |
CO | 39.62 | -106.38 | -41.3232 |
UT | 39.94 | -112.41 | -31.672 |
CA | 38.07 | -119.23 | -38.0598 |
MT | 47.92 | -112.79 | -0.68415 |
CA | 39.14 | -120.22 | -22.5402 |
NV | 39.13 | -114.96 | -23.989 |
MT | 46.27 | -113.16 | 10.68659 |
WY | 41.16 | -106.93 | -2.52073 |
UT | 37.58 | -112.9 | -32.9268 |
CO | 37.21 | -105.12 | -2.22805 |
MT | 44.61 | -111.15 | -7.30244 |
AZ | 35.14 | -112.15 | -53.4768 |
MT | 45.05 | -109.91 | 5.264634 |
UT | 37.84 | -111.88 | -16.222 |
CO | 40.35 | -106.1 | 5.385366 |
CO | 40.43 | -105.74 | 2.392683 |
OR | 45.07 | -118.15 | -18.0237 |
WY | 44.8 | -109.66 | -11.55 |
MT | 47.45 | -112.81 | -2.22805 |
AZ | 33.81 | -110.92 | -42.7579 |
MT | 48.17 | -109.65 | -25.6902 |
MT | 48.98 | -115.82 | 5.678049 |
MT | 44.66 | -111.09 | -20.561 |
MT | 46.13 | -113.31 | -3.69878 |
Figure 4. Change in Snowpack Season Length in the Western United States, 1982–2021
Data source: USDA Natural Resources Conservation Service, 2022
Web update: July 2022
Units: number of days of snow season duration
Key points
- From 1955 to 2022, April snow cover decreased at 93 percent of measured locations (see Figure 1). The average change across all sites is about a 23 percent decrease.
- A significant and consistent decrease in April snowpack was observed across the western United States (see Figure 1).
The decline was particularly pronounced in Washington, Oregon, northern California, and the Rockies. - While some stations saw an increase in April snowpack, all 12 states included in this indicator saw an average decrease between 1955 and 2022 (see Figure 1).
In the Northwest, all but three stations saw a decline in snow cover during the period of record. - About 84 percent of sites experienced a shift toward an earlier snowpack peak (see Figure 2). This earlier trend is particularly pronounced in southwestern states such as Colorado, New Mexico, and Utah.
At all stations, maximum snow cover has moved earlier by an average of nearly eight days since 1982 (see Figure 3), based on the long-term average rate of change. - From 1982 to 2021, the snowpack season shortened in about 86 percent of the locations where snowpack was measured. In all places, the length of the snow season was reduced by about 18 days on average.
Background
- Temperature and precipitation are key factors affecting snowpack, the amount or thickness of snow that accumulates on the ground.
In a warming climate, most areas are expected to see more precipitation as rain than snow – reducing the extent and depth of the snowpack.
Long-term observations in the contiguous 48 states show that nearly 80 percent of weather stations surveyed saw a decrease in the proportion of precipitation falling as snow.
In addition, with warmer winters and springs, the seasonality of the snow cover also changes. Warmer temperatures cause snow to melt earlier, which in turn affects the timing and availability of water. - Mountain snowpack plays a crucial role in the water cycle in western North America, storing water in the winter when snow falls and releasing it as runoff in the spring and summer when the snow melts.
Millions of people in the West depend on melting mountain snowpacks for hydropower, irrigation, and drinking water. In most western watersheds, the snowpack is a more prominent component of water supplies than man-made reservoirs. In the future, continued snowpack reductions and snowmelt shifts are expected to reduce hydropower generation in the Southwest and Northwest. - Changes in mountain snowpack can affect agriculture, winter recreation, and tourism in some areas, as well as plants and wildlife. For example, some species of trees rely on snow for insulation from frost, as do some species of animals.
In addition, fish spawning can be disrupted if changes in snow cover or snowmelt alter the timing and amount of flows. In addition, warming and earlier snowmelt are accelerating the start of the fire season and encouraging more wildfire activity in the western United States and Alaska.
The sensitivity of snowpack to climate and its many associated effects make it a valuable indicator to monitor.
About the indicator
- This indicator uses a measurement called snow water equivalent to determine snowpack trends. Snow water equivalent is the amount of water in the snow cover at a particular location.
It can be thought of as the depth of water that would be created if the entire snowpack melted. Figure 1 shows the long-term rate of change for April 1, the most common observation date, because it could reflect differences in precipitation and is widely used for spring streamflow and water supply forecasts.
Figures 2 and 3 focus on the day of each year when the snowpack is deepest to determine whether it occurs earlier or later.
Figure 4 shows changes in the length of the snowpack season, which represents the number of days the ground is covered with continuous snowpacks. - The USDA and other collaborators have measured snow cover since the early 20th century. In the early years of data collection, researchers measured snow water equivalent by hand.
Still, since 1980, measurements have been collected at some locations using automated instruments as part of a snow telemetry network. The long-term analysis in Figure 1 is based on data from nearly 700 permanent measurement sites in the western United States.
The snow cover analysis shown in Figures 2, 3, and 4 requires daily measurements, so it uses a smaller set of 328 SNOTEL sites that have data since 1982, when many SNOTEL devices were deployed and online.
About the Data
Notes on the indicator
- EPA chose 1955 as the starting point for Figure 1 because many measurement sites in the Southwest were established in the early 1950s. The natural variability of Earth’s climate means snowpack trends can vary slightly when measured over different periods.
For example, the period from 1945 to 1955 was unusually snowy in the Northwest, so if this indicator started in 1945 or 1950, the Northwest would appear to show more significant declines over time.
However, the general direction of the trend is the same regardless of the start date. The peak snow cover analysis in Figures 2, 3, and 4 is limited to automated SNOTEL stations, resulting in a shorter time and fewer stations than in Figure 1.
These analyzes are subject to less interannual variation than a single-date time series such as 1st April. However, snowpack conditions during the first few years (in this case, the early to mid-1980s) could still have a sizable influence on the trends calculated for this indicator. - Although most parts of the West experienced a decrease in snowpack—in line with the overall warming trends shown in the U.S. and the Global Temperature Indicator—snowfall trends may be partly influenced by non climatic factors such as observation methods, land use changes, and forest cover.
Changes. This indicator applies consistent methods to all locations, but each site naturally has unique local conditions and a unique distribution of data.
In many areas where the snowpack is increasing, studies have documented that despite general increases in temperature and precipitation, temperatures often remain below freezing, leading to more snow.
Data Sources
This indicator’s April 1 trend analysis was created using methods consistent with Mote et al. and Mote et al. peak snowpack analysis adapted from Evan’s work. Snowpack season length was calculated using Petersky and Harpold’s methods.
Weather 01852 - Lowell MA
49°
moderate rain
Feels like 49°06:33/19:06
52°F
/46°F
85%
1013 hPa
7 mi
1.01 mph