Last spring frost
Jun 11
Frost Dates for Brighton, UT
First fall frost
Sep 18
Growing season
98 days
Hardiness zone
6a
In an average year around Brighton, UT, the last spring frost (32°F) is about Jun 11 and the first fall frost is about Sep 18, giving roughly a 98-day growing season. To be safe most years, wait until May 26 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 27 | Jun 11 | May 26 |
| Hard (28°F) | Jun 18 | Jun 1 | May 14 |
| Severe (24°F) | Jun 6 | May 17 | Apr 30 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 27 | Jun 22 | Jun 18 | Jun 15 | Jun 11 | Jun 8 | Jun 5 | Jun 1 | May 26 |
| 28°F | Jun 18 | Jun 12 | Jun 8 | Jun 5 | Jun 1 | May 29 | May 24 | May 20 | May 14 |
| 24°F | Jun 6 | Jun 1 | May 26 | May 21 | May 17 | May 13 | May 9 | May 4 | Apr 30 |
| 20°F | May 26 | May 17 | May 12 | May 8 | May 5 | May 2 | Apr 29 | Apr 25 | Apr 20 |
| 16°F | May 10 | May 3 | Apr 29 | Apr 26 | Apr 22 | Apr 19 | Apr 15 | Apr 10 | Apr 4 |
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) | Sep 3 | Sep 18 | Sep 29 |
| Hard (28°F) | Sep 13 | Sep 27 | Oct 11 |
| Severe (24°F) | Sep 21 | Oct 5 | Oct 22 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Sep 3 | Sep 9 | Sep 13 | Sep 16 | Sep 18 | Sep 21 | Sep 23 | Sep 26 | Sep 29 |
| 28°F | Sep 13 | Sep 18 | Sep 22 | Sep 25 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 11 |
| 24°F | Sep 21 | Sep 27 | Sep 30 | Oct 3 | Oct 5 | Oct 9 | Oct 12 | Oct 17 | Oct 22 |
| 20°F | Oct 2 | Oct 5 | Oct 10 | Oct 13 | Oct 17 | Oct 20 | Oct 23 | Oct 27 | Nov 1 |
| 16°F | Oct 12 | Oct 17 | Oct 22 | Oct 25 | Oct 28 | Nov 1 | Nov 4 | 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: Alta, Ut, about 3.2 miles away@if(!empty($station['elevation_ft'])), at 8,710 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 Brighton, UT?
On average, the last spring frost (32°F) around Brighton, UT is about Jun 11. In cooler years it can run later, so for a safer bet many gardeners wait until May 26.
When is the first frost in the fall?
The first fall frost around Brighton, UT typically arrives about Sep 18. 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 Jun 11 on average, or May 26 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 98 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 84121 Planting calendar → Utah frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026