Frost dates for 84540Thompson, UT
The average last spring frost in Thompson is April 22 and the average first fall frost is October 20, giving a typical growing season of about 179 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 22
- Average first fall frost
- Oct 20
- Growing season
- 179 days
Safer after May 8 (1-in-10 risk)
Possible by Oct 6 (1-in-10 risk)
Last frost typically in 177 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) | Apr 20 · May 3 · May 20 | Sep 28 · Oct 10 · Oct 22 | 158 days | 100% |
| Frost / freeze (32°F) | Apr 7 · Apr 22 · May 8 | Oct 6 · Oct 20 · Nov 1 | 179 days | 100% |
| Hard freeze (28°F) | Mar 21 · Apr 8 · Apr 27 | Oct 15 · Oct 30 · Nov 9 | 202 days | 100% |
Planting calendar for Thompson
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 | Mar 22 – May 28 |
| Tomatoes | Transplant outdoors | May 8 – Jun 30 |
| Peppers | Start seeds indoors | Mar 22 – Apr 22 |
| Peppers | Transplant outdoors | May 22 – Jun 22 |
| Eggplant | Start seeds indoors | Apr 8 – May 7 |
| Eggplant | Transplant outdoors | May 22 – Jun 22 |
| Cucumbers | Sow outdoors | May 22 – Jul 10 |
| Summer squash | Sow outdoors | May 8 – Jun 22 |
| Winter squash & pumpkins | Sow outdoors | May 22 – Jun 22 |
| Snap beans | Sow outdoors | May 8 – Aug 2 |
| Sweet corn | Sow outdoors | May 8 – Jun 30 |
| Watermelon & cantaloupe | Sow outdoors | May 22 – Jun 22 |
| Okra | Sow outdoors | May 15 – Jun 7 |
| Peas | Sow outdoors (spring) | Mar 22 – May 7 |
| Potatoes | Plant outdoors (spring) | Mar 22 – May 22 |
| Onions | Start seeds indoors (spring) | Feb 8 – Mar 7 |
| Onions | Transplant outdoors (spring) | Apr 8 – May 7 |
| Broccoli | Start seeds indoors (spring) | Mar 4 – Apr 7 |
| Broccoli | Transplant outdoors (spring) | Apr 8 – May 7 |
| Broccoli | Start seeds indoors (fall) | Jun 20 – Jun 30 |
| Broccoli | Transplant outdoors (fall) | Jul 20 – Jul 31 |
| Cabbage | Start seeds indoors (spring) | Feb 22 – Mar 22 |
| Cabbage | Transplant outdoors (spring) | Mar 22 – Apr 22 |
| Cabbage | Start seeds indoors (fall) | Jun 10 – Jul 10 |
| Cabbage | Transplant outdoors (fall) | Jul 10 – Aug 10 |
| Leaf lettuce | Sow outdoors (spring) | Mar 22 – Jun 7 |
| Leaf lettuce | Sow outdoors (fall) | Jul 10 – Aug 26 |
| Spinach | Sow outdoors (spring) | Mar 15 – Apr 28 |
| Spinach | Sow outdoors (fall) | Jul 27 – Aug 31 |
| Radishes | Sow outdoors (spring) | Mar 22 – May 12 |
| Radishes | Sow outdoors (fall) | Jul 10 – Sep 10 |
| Kale | Sow outdoors (spring) | Apr 8 – Apr 28 |
| Kale | Sow outdoors (fall) | Jul 3 – Aug 10 |
| Carrots | Sow outdoors (spring) | Apr 22 – Jun 7 |
| Carrots | Sow outdoors (fall) | Jun 10 – Jul 26 |
| Garlic | Plant outdoors (fall) | Oct 10 – Nov 10 |
Where these dates come from
ZIP code 84540 is matched to the NOAA station Moab Canyonland Ap, UT, 24.3 km away, at 4,561 ft elevation (580 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Moab Canyonland Ap, UT (used) | 4,561 ft | Apr 22 | Oct 20 |
| Dewey, UT | 4,120 ft | Apr 27 | Oct 9 |
| Arches Np Hqs, UT | 4,093 ft | Apr 2 | Oct 30 |
| Castle Valley, UT | 4,725 ft | Apr 17 | Oct 23 |
Frost dates near Thompson
- Cisco, UT 84515 · last Apr 27, first Oct 9
- Green River, UT 84525 · last Apr 2, first Oct 30
- Moab, UT 84532 · last Apr 11, first Oct 23
- Gateway, CO 81522 · last Apr 20, first Oct 21
- Mack, CO 81525 · last Apr 27, first Oct 11
- Glade Park, CO 81523 · last May 21, first Sep 26
- Loma, CO 81524 · last Apr 27, first Oct 11
- La Sal, UT 84530 · last May 17, first Oct 6
Frequently asked questions
- When is the last frost in Thompson, UT?
- For ZIP code 84540, the average last spring frost (32°F) is April 22, based on NOAA 1991-2020 climate normals for the Moab Canyonland Ap, UT weather station. There is a 1-in-10 chance of a frost after May 8.
- When is the first frost in Thompson, UT?
- The average first fall frost (32°F) is October 20. There is a 1-in-10 chance of frost by October 6, so tender plants are at risk from that point on.
- How long is the growing season in 84540?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 179 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.