Last spring frost
Jun 15
Frost Dates for Helper, UT
First fall frost
Sep 12
Growing season
87 days
Hardiness zone
6a
In an average year around Helper, UT, the last spring frost (32°F) is about Jun 15 and the first fall frost is about Sep 12, giving roughly a 87-day growing season. To be safe most years, wait until Jun 2 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) | Jul 1 | Jun 15 | Jun 2 |
| Hard (28°F) | Jun 19 | Jun 3 | May 18 |
| Severe (24°F) | Jun 8 | May 19 | May 2 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jul 1 | Jun 26 | Jun 22 | Jun 19 | Jun 15 | Jun 13 | Jun 9 | Jun 6 | Jun 2 |
| 28°F | Jun 19 | Jun 13 | Jun 9 | Jun 6 | Jun 3 | May 31 | May 28 | May 23 | May 18 |
| 24°F | Jun 8 | Jun 1 | May 26 | May 22 | May 19 | May 15 | May 11 | May 7 | May 2 |
| 20°F | May 23 | May 15 | May 9 | May 5 | May 2 | Apr 30 | Apr 27 | Apr 23 | Apr 19 |
| 16°F | May 6 | May 1 | Apr 27 | Apr 22 | Apr 20 | Apr 16 | Apr 13 | Apr 9 | 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) | Aug 29 | Sep 12 | Sep 24 |
| Hard (28°F) | Sep 8 | Sep 21 | Oct 5 |
| Severe (24°F) | Sep 18 | Oct 2 | Oct 16 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 29 | Sep 4 | Sep 7 | Sep 9 | Sep 12 | Sep 15 | Sep 17 | Sep 20 | Sep 24 |
| 28°F | Sep 8 | Sep 12 | Sep 16 | Sep 19 | Sep 21 | Sep 24 | Sep 27 | Sep 30 | Oct 5 |
| 24°F | Sep 18 | Sep 23 | Sep 26 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 12 | Oct 16 |
| 20°F | Sep 28 | Oct 4 | Oct 7 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 24 | Oct 28 |
| 16°F | Oct 11 | Oct 16 | Oct 20 | Oct 23 | Oct 26 | Oct 28 | Oct 31 | Nov 4 | Nov 9 |
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: Scofield Dam, Ut, about 10.9 miles away@if(!empty($station['elevation_ft'])), at 7,630 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 Helper, UT?
On average, the last spring frost (32°F) around Helper, UT is about Jun 15. In cooler years it can run later, so for a safer bet many gardeners wait until Jun 2.
When is the first frost in the fall?
The first fall frost around Helper, UT typically arrives about Sep 12. 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 15 on average, or Jun 2 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 87 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 84526 Planting calendar → Utah frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026