Last spring frost
Jun 2
Frost Dates for Ophir, UT
First fall frost
Sep 16
Growing season
103 days
Hardiness zone
6b
In an average year around Ophir, UT, the last spring frost (32°F) is about Jun 2 and the first fall frost is about Sep 16, giving roughly a 103-day growing season. To be safe most years, wait until May 18 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 24 | Jun 2 | May 18 |
| Hard (28°F) | Jun 10 | May 19 | May 2 |
| Severe (24°F) | May 26 | May 4 | Apr 17 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 24 | Jun 17 | Jun 11 | Jun 7 | Jun 2 | May 31 | May 28 | May 23 | May 18 |
| 28°F | Jun 10 | Jun 1 | May 27 | May 23 | May 19 | May 15 | May 12 | May 8 | May 2 |
| 24°F | May 26 | May 18 | May 12 | May 8 | May 4 | Apr 30 | Apr 27 | Apr 23 | Apr 17 |
| 20°F | May 8 | May 2 | Apr 27 | Apr 23 | Apr 19 | Apr 15 | Apr 11 | Apr 6 | Mar 30 |
| 16°F | Apr 23 | Apr 14 | Apr 8 | Apr 3 | Mar 30 | Mar 25 | Mar 19 | Mar 12 | Mar 6 |
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 1 | Sep 16 | Sep 29 |
| Hard (28°F) | Sep 10 | Sep 26 | Oct 7 |
| Severe (24°F) | Sep 23 | Oct 5 | Oct 19 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Sep 1 | Sep 6 | Sep 10 | Sep 13 | Sep 16 | Sep 18 | Sep 21 | Sep 24 | Sep 29 |
| 28°F | Sep 10 | Sep 17 | Sep 20 | Sep 23 | Sep 26 | Sep 29 | Oct 1 | Oct 3 | Oct 7 |
| 24°F | Sep 23 | Sep 28 | Oct 1 | Oct 3 | Oct 5 | Oct 7 | Oct 10 | Oct 15 | Oct 19 |
| 20°F | Oct 1 | Oct 5 | Oct 9 | Oct 12 | Oct 16 | Oct 19 | Oct 22 | Oct 26 | Oct 30 |
| 16°F | Oct 11 | Oct 18 | Oct 21 | Oct 25 | Oct 28 | Nov 1 | Nov 2 | Nov 6 | 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: Fairfield, Ut, about 11.3 miles away@if(!empty($station['elevation_ft'])), at 4,880 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 Ophir, UT?
On average, the last spring frost (32°F) around Ophir, UT is about Jun 2. In cooler years it can run later, so for a safer bet many gardeners wait until May 18.
When is the first frost in the fall?
The first fall frost around Ophir, UT typically arrives about Sep 16. 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 2 on average, or May 18 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 103 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 84071 Planting calendar → Utah frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026