Last spring frost
May 23
Frost Dates for Hulett, WY
First fall frost
Sep 24
Growing season
121 days
Hardiness zone
5a
In an average year around Hulett, WY, the last spring frost (32°F) is about May 23 and the first fall frost is about Sep 24, giving roughly a 121-day growing season. To be safe most years, wait until May 10 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%) |
|---|---|---|---|
| Light (36°F) | Jun 20 | Jun 5 | May 23 |
| Freeze (32°F) | Jun 3 | May 23 | May 10 |
| Hard (28°F) | May 25 | May 12 | Apr 30 |
| Severe (24°F) | May 16 | May 1 | Apr 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 20 | Jun 14 | Jun 11 | Jun 8 | Jun 5 | Jun 2 | May 31 | May 27 | May 23 |
| 32°F | Jun 3 | May 31 | May 28 | May 26 | May 23 | May 20 | May 17 | May 14 | May 10 |
| 28°F | May 25 | May 21 | May 17 | May 15 | May 12 | May 9 | May 6 | May 3 | Apr 30 |
| 24°F | May 16 | May 10 | May 6 | May 4 | May 1 | Apr 29 | Apr 26 | Apr 23 | Apr 18 |
| 20°F | May 5 | Apr 30 | Apr 27 | Apr 23 | Apr 20 | Apr 17 | Apr 13 | Apr 9 | Apr 3 |
| 16°F | Apr 25 | Apr 20 | Apr 16 | Apr 11 | Apr 8 | Apr 4 | Mar 31 | Mar 26 | Mar 16 |
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%) |
|---|---|---|---|
| Light (36°F) | Aug 28 | Sep 11 | Sep 27 |
| Freeze (32°F) | Sep 7 | Sep 24 | Oct 8 |
| Hard (28°F) | Sep 18 | Oct 4 | Oct 18 |
| Severe (24°F) | Sep 27 | Oct 13 | Oct 29 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 28 | Sep 1 | Sep 4 | Sep 7 | Sep 11 | Sep 14 | Sep 18 | Sep 22 | Sep 27 |
| 32°F | Sep 7 | Sep 13 | Sep 17 | Sep 21 | Sep 24 | Sep 28 | Oct 1 | Oct 3 | Oct 8 |
| 28°F | Sep 18 | Sep 24 | Sep 29 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 14 | Oct 18 |
| 24°F | Sep 27 | Oct 2 | Oct 7 | Oct 10 | Oct 13 | Oct 17 | Oct 20 | Oct 24 | Oct 29 |
| 20°F | Oct 4 | Oct 10 | Oct 15 | Oct 18 | Oct 22 | Oct 26 | Oct 29 | Nov 2 | Nov 7 |
| 16°F | Oct 12 | Oct 18 | Oct 23 | Oct 27 | Oct 31 | Nov 3 | Nov 7 | Nov 11 | Nov 18 |
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: Sundance 8 Nnw, Wy, about 13.8 miles away@if(!empty($station['elevation_ft'])), at 5,792 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 Hulett, WY?
On average, the last spring frost (32°F) around Hulett, WY is about May 23. In cooler years it can run later, so for a safer bet many gardeners wait until May 10.
When is the first frost in the fall?
The first fall frost around Hulett, WY typically arrives about Sep 24. 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 23 on average, or May 10 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 121 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 82710 Planting calendar → Wyoming frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026