Frost Dates for Washington, UT
In Washington, UT, the average last spring frost is around Mar 14 and the average first fall frost around Nov 10, for a growing season of about 239 days. For frost-tender plants, wait until Apr 6, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the St George, UT weather station, 7 miles away, elevation 2,857 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | Apr 6 | Oct 27 |
| 20% | Mar 31 | Nov 1 |
| 30% | Mar 25 | Nov 5 |
| 40% | Mar 19 | Nov 8 |
| 50% | Mar 14 | Nov 10 |
| 60% | Mar 11 | Nov 12 |
| 70% | Mar 8 | Nov 15 |
| 80% | Mar 4 | Nov 18 |
| 90% | Feb 27 | Nov 22 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | Apr 3 | Nov 1 |
| Frost / freeze (32°F) | Mar 14 | Nov 10 |
| Hard freeze (28°F) | Feb 27 | Nov 20 |
Planting calendar for Washington
Transplant Mar 21 – Apr 4
Transplant Mar 28 – Apr 11
Transplant Mar 28 – Apr 11
Transplant Mar 21 – Apr 4
Sow or transplant Mar 21 – Apr 4
Sow or transplant Mar 21 – Apr 4
Sow or transplant Mar 28 – Apr 11
Sow or transplant Feb 14 – Feb 28
Fall sowing Sep 15 – Oct 13
Fall sowing Sep 15 – Oct 6
Fall sowing Sep 1 – Sep 15
Sow or transplant Feb 14 – Feb 28
Fall sowing Sep 1 – Sep 29
Transplant Feb 28 – Mar 14
Fall sowing Aug 18 – Sep 1
Transplant Feb 21 – Mar 7
Fall sowing Aug 18 – Sep 1
Fall sowing Aug 18 – Sep 1
Fall sowing Sep 29 – Oct 20
Fall sowing Sep 1 – Sep 15
Plant Feb 14 – Feb 28
Based on the average last frost (Mar 14) and first frost (Nov 10). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.