Frost dates for 82714Devils Tower, WY
The average last spring frost in Devils Tower is May 23 and the average first fall frost is September 20, giving a typical growing season of about 118 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 23
- Average first fall frost
- Sep 20
- Growing season
- 118 days
Safer after Jun 6 (1-in-10 risk)
Possible by Sep 4 (1-in-10 risk)
Last frost typically in 208 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) | May 22 · Jun 4 · Jun 23 | Aug 27 · Sep 8 · Sep 23 | 95 days | 100% |
| Frost / freeze (32°F) | May 12 · May 23 · Jun 6 | Sep 4 · Sep 20 · Oct 4 | 118 days | 100% |
| Hard freeze (28°F) | May 2 · May 12 · May 24 | Sep 15 · Oct 1 · Oct 14 | 141 days | 100% |
Planting calendar for Devils Tower
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 | Apr 22 – Jun 28 |
| Tomatoes | Transplant outdoors | Jun 8 – May 31 |
| Peppers | Start seeds indoors | Apr 22 – May 23 |
| Peppers | Transplant outdoors | Jun 22 – Jul 23 |
| Eggplant | Start seeds indoors | May 9 – Jun 7 |
| Eggplant | Transplant outdoors | Jun 22 – Jul 23 |
| Cucumbers | Sow outdoors | Jun 22 – Jun 10 |
| Summer squash | Sow outdoors | Jun 8 – Jul 23 |
| Winter squash & pumpkins | Sow outdoors | Jun 22 – Jul 23 |
| Snap beans | Sow outdoors | Jun 8 – Jul 3 |
| Sweet corn | Sow outdoors | Jun 8 – May 31 |
| Watermelon & cantaloupe | Sow outdoors | Jun 22 – Jul 23 |
| Okra | Sow outdoors | Jun 15 – Jul 8 |
| Peas | Sow outdoors (spring) | Apr 22 – Jun 7 |
| Potatoes | Plant outdoors (spring) | Apr 22 – Jun 22 |
| Onions | Start seeds indoors (spring) | Mar 11 – Apr 7 |
| Onions | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (spring) | Apr 4 – May 8 |
| Broccoli | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (fall) | May 21 – May 31 |
| Broccoli | Transplant outdoors (fall) | Jun 20 – Jul 1 |
| Cabbage | Start seeds indoors (spring) | Mar 25 – Apr 22 |
| Cabbage | Transplant outdoors (spring) | Apr 22 – May 23 |
| Cabbage | Start seeds indoors (fall) | May 11 – Jun 10 |
| Cabbage | Transplant outdoors (fall) | Jun 10 – Jul 11 |
| Leaf lettuce | Sow outdoors (spring) | Apr 22 – Jul 8 |
| Leaf lettuce | Sow outdoors (fall) | Jun 10 – Jul 27 |
| Spinach | Sow outdoors (spring) | Apr 15 – May 29 |
| Spinach | Sow outdoors (fall) | Jun 27 – Aug 1 |
| Radishes | Sow outdoors (spring) | Apr 22 – Jun 12 |
| Radishes | Sow outdoors (fall) | Jun 10 – Aug 11 |
| Kale | Sow outdoors (spring) | May 9 – May 29 |
| Kale | Sow outdoors (fall) | Jun 3 – Jul 11 |
| Carrots | Sow outdoors (spring) | May 23 – Jul 8 |
| Carrots | Sow outdoors (fall) | May 11 – Jun 26 |
| Garlic | Plant outdoors (fall) | Sep 10 – Oct 11 |
Where these dates come from
ZIP code 82714 is matched to the NOAA station Devils Twr #2, WY, 6.9 km away, at 3,862 ft elevation (370 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Devils Twr #2, WY (used) | 3,862 ft | May 23 | Sep 20 |
| Hulett, WY | 3,758 ft | May 17 | Sep 23 |
| Sundance 8 Nnw, WY | 5,792 ft | May 23 | Sep 24 |
| Sundance, WY | 4,695 ft | May 21 | Sep 25 |
Frost dates near Devils Tower
- Moorcroft, WY 82721 · last May 21, first Sep 25
- Hulett, WY 82720 · last May 17, first Sep 23
- Alva, WY 82711 · last May 17, first Sep 23
- Sundance, WY 82729 · last May 21, first Sep 25
- Aladdin, WY 82710 · last May 7, first Oct 3
- Beulah, WY 82712 · last May 12, first Oct 2
- Upton, WY 82730 · last May 20, first Sep 23
- Rozet, WY 82727 · last May 22, first Sep 25
Frequently asked questions
- When is the last frost in Devils Tower, WY?
- For ZIP code 82714, the average last spring frost (32°F) is May 23, based on NOAA 1991-2020 climate normals for the Devils Twr #2, WY weather station. There is a 1-in-10 chance of a frost after June 6.
- When is the first frost in Devils Tower, WY?
- The average first fall frost (32°F) is September 20. There is a 1-in-10 chance of frost by September 4, so tender plants are at risk from that point on.
- How long is the growing season in 82714?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 118 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.