Last spring frost
Apr 25
Frost Dates for Mapleton, UT
First fall frost
Oct 18
Growing season
174 days
Hardiness zone
7a
In an average year around Mapleton, UT, the last spring frost (32°F) is about Apr 25 and the first fall frost is about Oct 18, giving roughly a 174-day growing season. To be safe most years, wait until Apr 10 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) | May 31 | May 11 | Apr 26 |
| Freeze (32°F) | May 13 | Apr 25 | Apr 10 |
| Hard (28°F) | Apr 25 | Apr 9 | Mar 20 |
| Severe (24°F) | Apr 12 | Mar 24 | Mar 5 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 31 | May 24 | May 19 | May 14 | May 11 | May 7 | May 4 | Apr 30 | Apr 26 |
| 32°F | May 13 | May 5 | May 2 | Apr 29 | Apr 25 | Apr 21 | Apr 18 | Apr 14 | Apr 10 |
| 28°F | Apr 25 | Apr 19 | Apr 16 | Apr 12 | Apr 9 | Apr 6 | Apr 2 | Mar 29 | Mar 20 |
| 24°F | Apr 12 | Apr 6 | Apr 1 | Mar 28 | Mar 24 | Mar 19 | Mar 14 | Mar 9 | Mar 5 |
| 20°F | Mar 29 | Mar 22 | Mar 15 | Mar 10 | Mar 7 | Mar 3 | Feb 28 | Feb 25 | Feb 18 |
| 16°F | Mar 10 | Mar 4 | Feb 28 | Feb 26 | Feb 23 | Feb 19 | Feb 14 | Feb 8 | 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 22 | Oct 6 | Oct 20 |
| Freeze (32°F) | Oct 4 | Oct 18 | Nov 1 |
| Hard (28°F) | Oct 14 | Oct 30 | Nov 13 |
| Severe (24°F) | Oct 24 | Nov 9 | Nov 24 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 22 | Sep 28 | Oct 1 | Oct 3 | Oct 6 | Oct 9 | Oct 12 | Oct 16 | Oct 20 |
| 32°F | Oct 4 | Oct 8 | Oct 12 | Oct 15 | Oct 18 | Oct 21 | Oct 23 | Oct 27 | Nov 1 |
| 28°F | Oct 14 | Oct 19 | Oct 23 | Oct 26 | Oct 30 | Nov 2 | Nov 5 | Nov 8 | Nov 13 |
| 24°F | Oct 24 | Oct 31 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 20 | Nov 24 |
| 20°F | Nov 1 | Nov 7 | Nov 11 | Nov 15 | Nov 19 | Nov 22 | Nov 26 | Nov 29 | Dec 3 |
| 16°F | Nov 10 | Nov 16 | Nov 21 | Nov 24 | Nov 27 | Nov 30 | Dec 3 | Dec 7 | Dec 13 |
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: Spanish Fk Pwr House, Ut, about 3.5 miles away@if(!empty($station['elevation_ft'])), at 4,720 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 Mapleton, UT?
On average, the last spring frost (32°F) around Mapleton, UT is about Apr 25. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 10.
When is the first frost in the fall?
The first fall frost around Mapleton, UT typically arrives about Oct 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 Apr 25 on average, or Apr 10 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 174 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 84664 Planting calendar → Utah frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026