Last spring frost
May 28
Frost Dates for Elk Mountain, WY
First fall frost
Sep 13
Growing season
108 days
Hardiness zone
5a
In an average year around Elk Mountain, WY, the last spring frost (32°F) is about May 28 and the first fall frost is about Sep 13, giving roughly a 108-day growing season. To be safe most years, wait until May 14 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Freeze (32°F) | Jun 13 | May 28 | May 14 |
| Hard (28°F) | May 29 | May 13 | May 1 |
| Severe (24°F) | May 16 | May 3 | Apr 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 13 | Jun 5 | Jun 2 | May 31 | May 28 | May 25 | May 22 | May 18 | May 14 |
| 28°F | May 29 | May 23 | May 19 | May 16 | May 13 | May 11 | May 8 | May 5 | May 1 |
| 24°F | May 16 | May 11 | May 9 | May 6 | May 3 | May 1 | Apr 29 | Apr 24 | Apr 18 |
| 20°F | May 10 | May 4 | May 1 | Apr 27 | Apr 24 | Apr 19 | Apr 15 | Apr 11 | Apr 6 |
| 16°F | May 2 | Apr 25 | Apr 20 | Apr 15 | Apr 11 | Apr 8 | Apr 4 | Apr 1 | Mar 24 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Freeze (32°F) | Aug 30 | Sep 13 | Oct 1 |
| Hard (28°F) | Sep 9 | Sep 26 | Oct 12 |
| Severe (24°F) | Sep 21 | Oct 8 | Oct 24 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 30 | Sep 4 | Sep 7 | Sep 11 | Sep 13 | Sep 16 | Sep 20 | Sep 24 | Oct 1 |
| 28°F | Sep 9 | Sep 15 | Sep 19 | Sep 23 | Sep 26 | Sep 30 | Oct 3 | Oct 7 | Oct 12 |
| 24°F | Sep 21 | Sep 27 | Oct 1 | Oct 5 | Oct 8 | Oct 11 | Oct 15 | Oct 19 | Oct 24 |
| 20°F | Oct 2 | Oct 6 | Oct 10 | Oct 14 | Oct 18 | Oct 21 | Oct 25 | Oct 29 | Nov 3 |
| 16°F | Oct 8 | Oct 14 | Oct 18 | Oct 22 | Oct 26 | Oct 30 | Nov 3 | Nov 7 | Nov 12 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Elk Mtn, Wy, about 2.1 miles away@if(!empty($station['elevation_ft'])), at 7,265 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Elk Mountain, WY?
On average, the last spring frost (32°F) around Elk Mountain, WY is about May 28. In cooler years it can run later, so for a safer bet many gardeners wait until May 14.
When is the first frost in the fall?
The first fall frost around Elk Mountain, WY typically arrives about Sep 13. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around May 28 on average, or May 14 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 108 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 82324 Planting calendar → Wyoming frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026