Last spring frost
Mar 14
Frost Dates for Washington, UT
First fall frost
Nov 10
Growing season
239 days
Hardiness zone
8b
In an average year around Washington, UT, the last spring frost (32°F) is about Mar 14 and the first fall frost is about Nov 10, giving roughly a 239-day growing season. To be safe most years, wait until Feb 27 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) | Apr 21 | Apr 3 | Mar 17 |
| Freeze (32°F) | Apr 6 | Mar 14 | Feb 27 |
| Hard (28°F) | Mar 17 | Feb 27 | Feb 7 |
| Severe (24°F) | Feb 28 | Feb 9 | Jan 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 21 | Apr 15 | Apr 11 | Apr 8 | Apr 3 | Mar 31 | Mar 27 | Mar 22 | Mar 17 |
| 32°F | Apr 6 | Mar 31 | Mar 25 | Mar 19 | Mar 14 | Mar 11 | Mar 8 | Mar 4 | Feb 27 |
| 28°F | Mar 17 | Mar 10 | Mar 5 | Mar 1 | Feb 27 | Feb 24 | Feb 20 | Feb 15 | Feb 7 |
| 24°F | Feb 28 | Feb 22 | Feb 18 | Feb 13 | Feb 9 | Feb 6 | Feb 2 | Jan 27 | Jan 18 |
| 20°F | Feb 13 | Feb 6 | Feb 2 | Jan 28 | Jan 21 | Jan 14 | Jan 6 | Jan 1 | Dec 22 |
| 16°F | Jan 28 | Jan 20 | Jan 11 | Jan 5 | Jan 2 | Dec 31 | Dec 24 | Dec 20 | Dec 11 |
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) | Oct 19 | Nov 1 | Nov 12 |
| Freeze (32°F) | Oct 27 | Nov 10 | Nov 22 |
| Hard (28°F) | Nov 7 | Nov 20 | Dec 3 |
| Severe (24°F) | Nov 18 | Dec 1 | Dec 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 19 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 6 | Nov 9 | Nov 12 |
| 32°F | Oct 27 | Nov 1 | Nov 5 | Nov 8 | Nov 10 | Nov 12 | Nov 15 | Nov 18 | Nov 22 |
| 28°F | Nov 7 | Nov 13 | Nov 15 | Nov 18 | Nov 20 | Nov 22 | Nov 25 | Nov 29 | Dec 3 |
| 24°F | Nov 18 | Nov 22 | Nov 24 | Nov 28 | Dec 1 | Dec 4 | Dec 8 | Dec 12 | Dec 18 |
| 20°F | Nov 27 | Dec 4 | Dec 8 | Dec 11 | Dec 16 | Dec 20 | Dec 27 | Jan 1 | Jan 13 |
| 16°F | Dec 5 | Dec 11 | Dec 16 | Dec 21 | Dec 25 | Dec 30 | Jan 1 | Jan 6 | Jan 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: St George, Ut, about 7.4 miles away@if(!empty($station['elevation_ft'])), at 2,857 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 Washington, UT?
On average, the last spring frost (32°F) around Washington, UT is about Mar 14. In cooler years it can run later, so for a safer bet many gardeners wait until Feb 27.
When is the first frost in the fall?
The first fall frost around Washington, UT typically arrives about Nov 10. 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 Mar 14 on average, or Feb 27 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 239 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 84780 Planting calendar → Utah frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026