From NOAA 1991–2020 normals
The Latest Last Frost and the Earliest First Frost in the US
The towns with the latest spring frost, the earliest fall frost and the shortest freeze-free seasons, from NOAA station normals.
Among the 4,701 stations behind indexed pages where frost comes every year, the latest 50% last spring frost is at Nederland, CO, June 21; the earliest first fall frost at Jackson, WY, August 31. The fifteen latest springs are at a median height of 7,752 feet, against 800 feet for all of these stations.
Latest last spring frost
| Place | Station | Height, ft | Last frost | Season |
|---|---|---|---|---|
| Nederland, CO | Boulder 14 W, CO | 9,828 | June 21 | 71 d |
| Colorado Springs, CO | Vail, CO | 8,304 | June 21 | 77 d |
| Gunnison, CO | Cochetopa Creek, CO | 8,006 | June 21 | 74 d |
| Parowan, UT | Brian Head, UT | 9,770 | June 21 | 82 d |
| Afton, WY | Afton, WY | 6,248 | June 20 | 71 d |
| Crested Butte, CO | Taylor Park, CO | 9,179 | June 20 | 80 d |
| Jackson, WY | Moose, WY | 6,444 | June 20 | 70 d |
| Clancy, MT | Tizer Gardens, MT | 4,672 | June 18 | 81 d |
| Montpelier, ID | Bern, ID | 5,964 | June 17 | 77 d |
| Grand Canyon, AZ | Grand Canyon Np Airport, AZ | 6,606 | June 17 | 97 d |
| Bailey, CO | Bailey, CO | 7,752 | June 16 | 84 d |
| Breckenridge, CO | Fairplay S Park Rd, CO | 9,995 | June 16 | 83 d |
| Ennis, MT | Ennis, MT | 4,953 | June 16 | 78 d |
| Leadville, CO | Twin Lakes Rsvr, CO | 9,236 | June 16 | 85 d |
| Tetonia, ID | Tetonia Exp Stn, ID | 6,170 | June 15 | 85 d |
Earliest first fall frost
| Place | Station | Height, ft | First frost | Season |
|---|---|---|---|---|
| Jackson, WY | Moose, WY | 6,444 | August 31 | 70 d |
| Afton, WY | Afton, WY | 6,248 | September 1 | 71 d |
| Kasilof, AK | Soldotna 5SSW, AK | 180 | September 1 | 75 d |
| Eielson Afb, AK | Eielson Field, AK | 547 | September 1 | 104 d |
| Nederland, CO | Boulder 14 W, CO | 9,828 | September 2 | 71 d |
| North Pole, AK | N Pole 1N, AK | 496 | September 2 | 102 d |
| Montpelier, ID | Bern, ID | 5,964 | September 3 | 77 d |
| Nome, AK | Nome Municipal Airport, AK | 13 | September 3 | 88 d |
| Laramie, WY | Laramie 2 NW, WY | 7,140 | September 4 | 88 d |
| Big Piney, WY | La Barge, WY | 6,598 | September 4 | 84 d |
| Ennis, MT | Ennis, MT | 4,953 | September 4 | 78 d |
| Cheney, WA | Spokane 17 SSW, WA | 2,267 | September 4 | 94 d |
| Kremmling, CO | Kremmling, CO | 7,460 | September 5 | 80 d |
| Gunnison, CO | Cochetopa Creek, CO | 8,006 | September 5 | 74 d |
| Clancy, MT | Tizer Gardens, MT | 4,672 | September 5 | 81 d |
Shortest freeze-free seasons
| Place | Height, ft | Last frost | First frost | Season |
|---|---|---|---|---|
| Jackson, WY | 6,444 | June 20 | August 31 | 70 d |
| Nederland, CO | 9,828 | June 21 | September 2 | 71 d |
| Afton, WY | 6,248 | June 20 | September 1 | 71 d |
| Gunnison, CO | 8,006 | June 21 | September 5 | 74 d |
| Kasilof, AK | 180 | June 11 | September 1 | 75 d |
| Colorado Springs, CO | 8,304 | June 21 | September 7 | 77 d |
| Montpelier, ID | 5,964 | June 17 | September 3 | 77 d |
| Ennis, MT | 4,953 | June 16 | September 4 | 78 d |
| Kremmling, CO | 7,460 | June 14 | September 5 | 80 d |
| Crested Butte, CO | 9,179 | June 20 | September 8 | 80 d |
| Clancy, MT | 4,672 | June 18 | September 5 | 81 d |
| Parowan, UT | 9,770 | June 21 | September 12 | 82 d |
| Breckenridge, CO | 9,995 | June 16 | September 9 | 83 d |
| Butte, MT | 5,506 | June 13 | September 5 | 83 d |
| Saratoga, WY | 6,801 | June 12 | September 7 | 83 d |
Computed by ArtUp Labs from NOAA NCEI U.S. Climate Normals for the stations behind this site's indexed ZIP pages, one row per station. Methodology · All guides