Frost dates for 84780Washington, UT
The average last spring frost in Washington is March 14 and the average first fall frost is November 10, giving a typical growing season of about 239 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 14
- Average first fall frost
- Nov 10
- Growing season
- 239 days
Safer after Apr 6 (1-in-10 risk)
Possible by Oct 27 (1-in-10 risk)
First frost typically in 14 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Mar 17 · Apr 3 · Apr 21 | Oct 19 · Nov 1 · Nov 12 | 208 days | 100% |
| Frost / freeze (32°F) | Feb 27 · Mar 14 · Apr 6 | Oct 27 · Nov 10 · Nov 22 | 239 days | 100% |
| Hard freeze (28°F) | Feb 7 · Feb 27 · Mar 17 | Nov 7 · Nov 20 · Dec 3 | 266 days | 100% |
Planting calendar for Washington
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Feb 11 – Apr 19 |
| Tomatoes | Transplant outdoors | Mar 30 – Jul 21 |
| Peppers | Start seeds indoors | Feb 11 – Mar 14 |
| Peppers | Transplant outdoors | Apr 13 – May 14 |
| Eggplant | Start seeds indoors | Feb 28 – Mar 29 |
| Eggplant | Transplant outdoors | Apr 13 – May 14 |
| Cucumbers | Sow outdoors | Apr 13 – Jul 31 |
| Summer squash | Sow outdoors | Mar 30 – May 14 |
| Winter squash & pumpkins | Sow outdoors | Apr 13 – May 14 |
| Snap beans | Sow outdoors | Mar 30 – Aug 23 |
| Sweet corn | Sow outdoors | Mar 30 – Jul 21 |
| Watermelon & cantaloupe | Sow outdoors | Apr 13 – May 14 |
| Okra | Sow outdoors | Apr 6 – Apr 29 |
| Peas | Sow outdoors (spring) | Feb 11 – Mar 29 |
| Potatoes | Plant outdoors (spring) | Feb 11 – Apr 13 |
| Onions | Start seeds indoors (spring) | Dec 31 – Jan 27 |
| Onions | Transplant outdoors (spring) | Feb 28 – Mar 29 |
| Broccoli | Start seeds indoors (spring) | Jan 24 – Feb 27 |
| Broccoli | Transplant outdoors (spring) | Feb 28 – Mar 29 |
| Broccoli | Start seeds indoors (fall) | Jul 11 – Jul 21 |
| Broccoli | Transplant outdoors (fall) | Aug 10 – Aug 21 |
| Cabbage | Start seeds indoors (spring) | Jan 14 – Feb 11 |
| Cabbage | Transplant outdoors (spring) | Feb 11 – Mar 14 |
| Cabbage | Start seeds indoors (fall) | Jul 1 – Jul 31 |
| Cabbage | Transplant outdoors (fall) | Jul 31 – Aug 31 |
| Leaf lettuce | Sow outdoors (spring) | Feb 11 – Apr 29 |
| Leaf lettuce | Sow outdoors (fall) | Jul 31 – Sep 16 |
| Spinach | Sow outdoors (spring) | Feb 4 – Mar 20 |
| Spinach | Sow outdoors (fall) | Aug 17 – Sep 21 |
| Radishes | Sow outdoors (spring) | Feb 11 – Apr 3 |
| Radishes | Sow outdoors (fall) | Jul 31 – Oct 1 |
| Kale | Sow outdoors (spring) | Feb 28 – Mar 20 |
| Kale | Sow outdoors (fall) | Jul 24 – Aug 31 |
| Carrots | Sow outdoors (spring) | Mar 14 – Apr 29 |
| Carrots | Sow outdoors (fall) | Jul 1 – Aug 16 |
| Garlic | Plant outdoors (fall) | Oct 31 – Dec 1 |
Where these dates come from
ZIP code 84780 is matched to the NOAA station St George, UT, 9.2 km away, at 2,857 ft elevation (20 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| St George, UT (used) | 2,857 ft | Mar 14 | Nov 10 |
| La Verkin, UT | 3,194 ft | Apr 1 | Nov 5 |
| Veyo Powerhouse, UT | 4,600 ft | Apr 9 | Nov 5 |
| New Harmony, UT | 5,167 ft | May 9 | Oct 11 |
Frost dates near Washington
- Saint George, UT 84790 · last Mar 14, first Nov 10
- Hurricane, UT 84737 · last Apr 1, first Nov 5
- Santa Clara, UT 84765 · last Mar 14, first Nov 10
- Leeds, UT 84746 · last Apr 1, first Nov 5
- Ivins, UT 84738 · last Mar 14, first Nov 10
- Dammeron Valley, UT 84783 · last Apr 9, first Nov 5
- Toquerville, UT 84774 · last Apr 1, first Nov 5
- La Verkin, UT 84745 · last Apr 13, first Nov 2
Frequently asked questions
- When is the last frost in Washington, UT?
- For ZIP code 84780, the average last spring frost (32°F) is March 14, based on NOAA 1991-2020 climate normals for the St George, UT weather station. There is a 1-in-10 chance of a frost after April 6.
- When is the first frost in Washington, UT?
- The average first fall frost (32°F) is November 10. There is a 1-in-10 chance of frost by October 27, so tender plants are at risk from that point on.
- How long is the growing season in 84780?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 239 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.