Last spring frost
May 13
Frost Dates for Atlantic City, WY
First fall frost
Oct 2
Growing season
140 days
Hardiness zone
5a
In an average year around Atlantic City, WY, the last spring frost (32°F) is about May 13 and the first fall frost is about Oct 2, giving roughly a 140-day growing season. To be safe most years, wait until May 1 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 13 | May 29 | May 14 |
| Freeze (32°F) | Jun 1 | May 13 | May 1 |
| Hard (28°F) | May 16 | May 1 | Apr 18 |
| Severe (24°F) | May 2 | Apr 20 | Apr 3 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 13 | Jun 7 | Jun 4 | May 31 | May 29 | May 25 | May 22 | May 18 | May 14 |
| 32°F | Jun 1 | May 25 | May 20 | May 16 | May 13 | May 10 | May 8 | May 5 | May 1 |
| 28°F | May 16 | May 10 | May 6 | May 3 | May 1 | Apr 29 | Apr 26 | Apr 22 | Apr 18 |
| 24°F | May 2 | Apr 29 | Apr 26 | Apr 23 | Apr 20 | Apr 17 | Apr 12 | Apr 8 | Apr 3 |
| 20°F | Apr 24 | Apr 20 | Apr 14 | Apr 9 | Apr 5 | Apr 2 | Mar 31 | Mar 25 | Mar 16 |
| 16°F | Apr 14 | Apr 7 | Apr 2 | Mar 30 | Mar 24 | Mar 19 | Mar 14 | Mar 10 | Mar 5 |
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) | Sep 10 | Sep 22 | Oct 4 |
| Freeze (32°F) | Sep 20 | Oct 2 | Oct 15 |
| Hard (28°F) | Sep 30 | Oct 13 | Oct 24 |
| Severe (24°F) | Oct 6 | Oct 21 | Nov 3 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 10 | Sep 14 | Sep 17 | Sep 20 | Sep 22 | Sep 24 | Sep 27 | Sep 30 | Oct 4 |
| 32°F | Sep 20 | Sep 25 | Sep 28 | Oct 1 | Oct 2 | Oct 5 | Oct 7 | Oct 11 | Oct 15 |
| 28°F | Sep 30 | Oct 3 | Oct 6 | Oct 9 | Oct 13 | Oct 15 | Oct 18 | Oct 21 | Oct 24 |
| 24°F | Oct 6 | Oct 11 | Oct 15 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 3 |
| 20°F | Oct 14 | Oct 19 | Oct 23 | Oct 26 | Oct 30 | Nov 1 | Nov 5 | Nov 8 | Nov 13 |
| 16°F | Oct 20 | Oct 26 | Oct 31 | Nov 4 | Nov 7 | Nov 10 | Nov 13 | Nov 16 | Nov 21 |
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: Lander 11 Sse, Wy, about 1.8 miles away@if(!empty($station['elevation_ft'])), at 5,773 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 Atlantic City, WY?
On average, the last spring frost (32°F) around Atlantic City, WY is about May 13. In cooler years it can run later, so for a safer bet many gardeners wait until May 1.
When is the first frost in the fall?
The first fall frost around Atlantic City, WY typically arrives about Oct 2. 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 13 on average, or May 1 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 140 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 82520 Planting calendar → Wyoming frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026