Last spring frost
May 4
Frost Dates for Fillmore, UT
First fall frost
Oct 14
Growing season
160 days
Hardiness zone
6a
In an average year around Fillmore, UT, the last spring frost (32°F) is about May 4 and the first fall frost is about Oct 14, giving roughly a 160-day growing season. To be safe most years, wait until Apr 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%) |
|---|---|---|---|
| Light (36°F) | Jun 8 | May 20 | May 1 |
| Freeze (32°F) | May 26 | May 4 | Apr 18 |
| Hard (28°F) | May 9 | Apr 19 | Mar 30 |
| Severe (24°F) | Apr 21 | Mar 30 | Mar 6 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 8 | Jun 1 | May 28 | May 24 | May 20 | May 15 | May 12 | May 7 | May 1 |
| 32°F | May 26 | May 18 | May 12 | May 8 | May 4 | May 1 | Apr 28 | Apr 24 | Apr 18 |
| 28°F | May 9 | May 2 | Apr 27 | Apr 23 | Apr 19 | Apr 15 | Apr 10 | Apr 5 | Mar 30 |
| 24°F | Apr 21 | Apr 13 | Apr 7 | Apr 3 | Mar 30 | Mar 25 | Mar 19 | Mar 12 | Mar 6 |
| 20°F | Apr 1 | Mar 23 | Mar 17 | Mar 12 | Mar 8 | Mar 5 | Mar 1 | Feb 25 | Feb 17 |
| 16°F | Mar 11 | Mar 4 | Feb 28 | Feb 25 | Feb 21 | Feb 18 | Feb 14 | Feb 10 | Feb 2 |
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 20 | Oct 2 | Oct 17 |
| Freeze (32°F) | Sep 30 | Oct 14 | Oct 28 |
| Hard (28°F) | Oct 9 | Oct 25 | Nov 8 |
| Severe (24°F) | Oct 19 | Nov 5 | Nov 19 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 20 | Sep 24 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 13 | Oct 17 |
| 32°F | Sep 30 | Oct 3 | Oct 7 | Oct 10 | Oct 14 | Oct 16 | Oct 19 | Oct 23 | Oct 28 |
| 28°F | Oct 9 | Oct 15 | Oct 18 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 3 | Nov 8 |
| 24°F | Oct 19 | Oct 25 | Oct 29 | Nov 1 | Nov 5 | Nov 7 | Nov 11 | Nov 15 | Nov 19 |
| 20°F | Oct 29 | Nov 3 | Nov 7 | Nov 12 | Nov 15 | Nov 18 | Nov 21 | Nov 25 | Nov 29 |
| 16°F | Nov 8 | Nov 14 | Nov 18 | Nov 22 | Nov 25 | Nov 28 | Dec 1 | Dec 6 | Dec 11 |
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: Fillmore, Ut, about 4.7 miles away@if(!empty($station['elevation_ft'])), at 5,127 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 Fillmore, UT?
On average, the last spring frost (32°F) around Fillmore, UT is about May 4. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 18.
When is the first frost in the fall?
The first fall frost around Fillmore, UT typically arrives about Oct 14. 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 4 on average, or Apr 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 160 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 84631 Planting calendar → Utah frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026