When Is the Last Frost in Utah?
The average last spring frost in Utah falls between April 10 and June 3 for most ZIP codes, with a statewide median of May 6. At the average date a later frost is still a coin flip, so tender plants wait for the safer 90% date.
| City | Last frost | 90% safe after | First frost | Growing season |
|---|---|---|---|---|
| Salt Lake City | Mar 31 | Apr 19 | Nov 8 | 224 days |
| West Valley City | Apr 8 | Apr 30 | Oct 31 | 204 days |
| West Jordan | Apr 18 | May 6 | Oct 22 | 185 days |
| Provo | Apr 18 | May 5 | Oct 21 | 185 days |
| St. George | Mar 14 | Apr 6 | Nov 10 | 239 days |
| Orem | Apr 19 | May 9 | Oct 19 | 182 days |
| Lehi | Apr 30 | May 27 | Oct 9 | 159 days |
| Sandy | Apr 29 | May 30 | Oct 22 | 174 days |
| Ogden | Apr 21 | May 6 | Oct 23 | 184 days |
| South Jordan | Apr 18 | May 6 | Oct 22 | 185 days |
| Logan | Apr 30 | May 19 | Oct 16 | 166 days |
| Tooele | May 2 | May 28 | Oct 16 | 165 days |
| Cedar City | May 21 | Jun 8 | Sep 29 | 130 days |
| Brigham City | May 5 | May 29 | Oct 5 | 150 days |
| Heber | May 31 | Jun 23 | Sep 11 | 101 days |
| Santaquin | May 4 | May 28 | Oct 11 | 157 days |
| Tremonton | Apr 24 | May 9 | Oct 17 | 175 days |
| Vernal | May 6 | May 25 | Oct 7 | 153 days |
Last and first frost: 50% (median) dates of the last spring and first fall 32 °F night. 90% safe after: only a 10% chance of a later spring frost. First frost dates in January fall in the following winter. Each city uses the NOAA station nearest the ZIP code closest to its center.
Across all 169 Utah weather stations with frost records, median last frost dates run from March 9 at Hite Rs, UT to June 21 at Brian Head, UT. Elevation, valleys that collect cold air and distance from large water bodies explain most of the spread, so a garden a few miles from a listed city can differ by a week or more. The ZIP code lookup above uses the same NOAA data as the frost date calculator for every US ZIP code.
When Is the First Frost in Utah?
The average first fall frost in Utah arrives between September 20 and October 31 for most ZIP codes, with a median of October 9. Tomatoes, peppers, basil and squash are damaged at 32 °F, so harvest or cover them before then.
Fall frost can come early: Salt Lake City has a 10% chance of frost before October 23, West Valley City has a 10% chance of frost before October 17 and West Jordan has a 10% chance of frost before October 7. Hardy crops such as kale, spinach and cabbage tolerate light frosts and keep producing after the first frost date.
When to Plant Tomatoes in Utah?
Transplant tomatoes in Utah 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: Apr 7 – Apr 14 in Salt Lake City, Apr 15 – Apr 22 in West Valley City and Apr 25 – May 2 in West Jordan. Start seeds indoors 6 to 8 weeks before the last frost.
| City | Start seeds indoors | Transplant outdoors | Lowest-risk transplant |
|---|---|---|---|
| Salt Lake City | Feb 3 – Feb 17 | Apr 7 – Apr 14 | after Apr 19 |
| West Valley City | Feb 11 – Feb 25 | Apr 15 – Apr 22 | after Apr 30 |
| West Jordan | Feb 21 – Mar 7 | Apr 25 – May 2 | after May 6 |
| Provo | Feb 21 – Mar 7 | Apr 25 – May 2 | after May 5 |
| St. George | Jan 17 – Jan 31 | Mar 21 – Mar 28 | after Apr 6 |
| Orem | Feb 22 – Mar 8 | Apr 26 – May 3 | after May 9 |
| Lehi | Mar 5 – Mar 19 | May 7 – May 14 | after May 27 |
| Sandy | Mar 4 – Mar 18 | May 6 – May 13 | after May 30 |
| Ogden | Feb 24 – Mar 10 | Apr 28 – May 5 | after May 6 |
| South Jordan | Feb 21 – Mar 7 | Apr 25 – May 2 | after May 6 |
| Logan | Mar 5 – Mar 19 | May 7 – May 14 | after May 19 |
| Tooele | Mar 7 – Mar 21 | May 9 – May 16 | after May 28 |
| Cedar City | Mar 26 – Apr 9 | May 28 – Jun 4 | after Jun 8 |
| Brigham City | Mar 10 – Mar 24 | May 12 – May 19 | after May 29 |
| Heber | Apr 5 – Apr 19 | Jun 7 – Jun 14 | after Jun 23 |
| Santaquin | Mar 9 – Mar 23 | May 11 – May 18 | after May 28 |
| Tremonton | Feb 27 – Mar 13 | May 1 – May 8 | after May 9 |
| Vernal | Mar 11 – Mar 25 | May 13 – May 20 | after May 25 |
Indoors: 6–8 weeks before the average last frost. Outdoors: 1–2 weeks after it. Lowest-risk: after the date with only a 10% chance of a later frost. Rules of thumb; check the 10-day forecast and wait for soil near 60 °F.
Tomatoes stall below about 50 °F at night and are killed by frost, so a week or two of waiting after the average date costs little. The tomato plant care guide covers light, watering and feeding once plants are in the ground.
What Can You Plant in Salt Lake City and When?
Salt Lake City's average last frost of March 31 anchors its spring planting calendar: peas and spinach go in from February 17, broccoli and lettuce transplants from March 3, and tomatoes, peppers and squash after April 7.
| Crop | Start seeds indoors | Plant outdoors | Frost tolerance |
|---|---|---|---|
| Peas | — | Feb 17 – Mar 3direct sow, 4–6 weeks before last frost | hardy |
| Spinach | — | Feb 17 – Mar 10direct sow, 3–6 weeks before last frost | hardy |
| Radishes | — | Feb 24 – Mar 10direct sow, 3–5 weeks before last frost | hardy |
| Onions (sets) | — | Mar 3 – Mar 17plant, 2–4 weeks before last frost | hardy |
| Potatoes | — | Mar 3 – Mar 17plant, 2–4 weeks before last frost | half-hardy |
| Broccoli & cabbage | Feb 3 – Feb 17 | Mar 3 – Mar 17transplant, 2–4 weeks before last frost | hardy |
| Lettuce | Feb 17 – Mar 3 | Mar 3 – Mar 17transplant, 2–4 weeks before last frost | hardy |
| Beets | — | Mar 3 – Mar 17direct sow, 2–4 weeks before last frost | half-hardy |
| Carrots | — | Mar 10 – Mar 17direct sow, 2–3 weeks before last frost | half-hardy |
| Tomatoes | Feb 3 – Feb 17 | Apr 7 – Apr 14transplant, 1–2 weeks after last frost | tender |
| Basil | Feb 3 – Feb 17 | Apr 7 – Apr 21transplant, 1–3 weeks after last frost | tender |
| Peppers | Jan 20 – Feb 3 | Apr 14 – Apr 21transplant, 2–3 weeks after last frost | tender |
| Eggplant | Jan 20 – Feb 3 | Apr 14 – Apr 21transplant, 2–3 weeks after last frost | tender |
| Green beans | — | Apr 7 – Apr 21direct sow, 1–3 weeks after last frost | tender |
| Sweet corn | — | Apr 7 – Apr 21direct sow, 1–3 weeks after last frost | tender |
| Cucumbers | Mar 3 – Mar 10 | Apr 7 – Apr 21transplant, 1–3 weeks after last frost | tender |
| Squash & zucchini | Mar 3 – Mar 10 | Apr 7 – Apr 21transplant, 1–3 weeks after last frost | tender |
| Watermelon | Mar 3 – Mar 10 | Apr 14 – Apr 21transplant, 2–3 weeks after last frost | tender |
Dates for Salt Lake City (last frost Mar 31, NOAA station Salt Lake Triad Ctr, UT, under 1 mile from ZIP 84180). General rules of thumb; wait for soil near 50 °F for most seeds and 60 °F for beans, corn and squash.
How Long Is the Growing Season in Utah?
The frost-free growing season in Utah lasts about 106 to 204 days for most ZIP codes, with a median of 155 days. Among the listed cities, Heber has the shortest season at 101 days and St. George the longest at 239.
Season length decides which varieties ripen: compare it with the “days to maturity” on seed packets, counted from transplanting for tomatoes and peppers. NOAA stations in Utah range from 76 days at Randolph, UT to 253 days at Hite Rs, UT. Planning beds before the season starts helps in short seasons — a plant spacing calculator for vegetable beds shows how many transplants fit.
What Hardiness Zones Are in Utah?
Utah spans USDA hardiness zones 4a to 8b, with zone 6a the most common. Zones describe winter cold and decide which perennials survive, while frost dates set when to plant annual vegetables and flowers.
The Utah planting zone map with the zone of each city shows how the zones are spread across the state and which plants are hardy in all of them.
Frequently Asked Questions
- When is the last frost in Utah?
- The average last spring frost in Utah falls between April 10 and June 3 for most ZIP codes, with a statewide median of May 6. Among major cities it ranges from March 14 in St. George to May 31 in Heber.
- When is the last frost in Salt Lake City, Utah?
- Salt Lake City's average last spring frost is March 31, and by April 19 the chance of a later frost drops to 10%. Its first fall frost averages November 8, giving a 224-day growing season (NOAA station Salt Lake Triad Ctr, UT).
- When should you plant tomatoes in Utah?
- Transplant tomatoes in Utah 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: Apr 7 – Apr 14 in Salt Lake City, Apr 15 – Apr 22 in West Valley City and Apr 25 – May 2 in West Jordan. Start seeds indoors 6 to 8 weeks before the last frost.
- When is the first frost in Utah?
- The average first fall frost in Utah arrives between September 20 and October 31 for most ZIP codes, with a median of October 9. Harvest tender crops such as tomatoes, peppers and basil before then or cover them on cold nights.
- How long is the growing season in Utah?
- The frost-free growing season in Utah lasts about 106 to 204 days for most ZIP codes, with a median of 155 days, from 101 days in Heber to 239 days in St. George.
Frost data: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals (32 °F freeze dates by probability). ZIP code and city locations and populations: U.S. Census Bureau Gazetteer files and Vintage 2024 population estimates. Planting windows are general rules of thumb. PlantoScan is not affiliated with or endorsed by these agencies.