Frost dates for 82435Powell, WY
The average last spring frost in Powell is May 19 and the average first fall frost is September 20, giving a typical growing season of about 123 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 19
- Average first fall frost
- Sep 20
- Growing season
- 123 days
Safer after Jun 4 (1-in-10 risk)
Possible by Sep 7 (1-in-10 risk)
Last frost typically in 204 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) | — | — | 94 days | 100% |
| Frost / freeze (32°F) | May 5 · May 19 · Jun 4 | Sep 7 · Sep 20 · Oct 1 | 123 days | 100% |
| Hard freeze (28°F) | Apr 25 · May 5 · May 20 | Sep 16 · Sep 29 · Oct 14 | 146 days | 100% |
Planting calendar for Powell
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 18 – Jun 24 |
| Tomatoes | Transplant outdoors | Jun 4 – May 31 |
| Peppers | Start seeds indoors | Apr 18 – May 19 |
| Peppers | Transplant outdoors | Jun 18 – Jul 19 |
| Eggplant | Start seeds indoors | May 5 – Jun 3 |
| Eggplant | Transplant outdoors | Jun 18 – Jul 19 |
| Cucumbers | Sow outdoors | Jun 18 – Jun 10 |
| Summer squash | Sow outdoors | Jun 4 – Jul 19 |
| Winter squash & pumpkins | Sow outdoors | Jun 18 – Jul 19 |
| Snap beans | Sow outdoors | Jun 4 – Jul 3 |
| Sweet corn | Sow outdoors | Jun 4 – May 31 |
| Watermelon & cantaloupe | Sow outdoors | Jun 18 – Jul 19 |
| Okra | Sow outdoors | Jun 11 – Jul 4 |
| Peas | Sow outdoors (spring) | Apr 18 – Jun 3 |
| Potatoes | Plant outdoors (spring) | Apr 18 – Jun 18 |
| Onions | Start seeds indoors (spring) | Mar 7 – Apr 3 |
| Onions | Transplant outdoors (spring) | May 5 – Jun 3 |
| Broccoli | Start seeds indoors (spring) | Mar 31 – May 4 |
| Broccoli | Transplant outdoors (spring) | May 5 – Jun 3 |
| Broccoli | Start seeds indoors (fall) | May 21 – May 31 |
| Broccoli | Transplant outdoors (fall) | Jun 20 – Jul 1 |
| Cabbage | Start seeds indoors (spring) | Mar 21 – Apr 18 |
| Cabbage | Transplant outdoors (spring) | Apr 18 – May 19 |
| Cabbage | Start seeds indoors (fall) | May 11 – Jun 10 |
| Cabbage | Transplant outdoors (fall) | Jun 10 – Jul 11 |
| Leaf lettuce | Sow outdoors (spring) | Apr 18 – Jul 4 |
| Leaf lettuce | Sow outdoors (fall) | Jun 10 – Jul 27 |
| Spinach | Sow outdoors (spring) | Apr 11 – May 25 |
| Spinach | Sow outdoors (fall) | Jun 27 – Aug 1 |
| Radishes | Sow outdoors (spring) | Apr 18 – Jun 8 |
| Radishes | Sow outdoors (fall) | Jun 10 – Aug 11 |
| Kale | Sow outdoors (spring) | May 5 – May 25 |
| Kale | Sow outdoors (fall) | Jun 3 – Jul 11 |
| Carrots | Sow outdoors (spring) | May 19 – Jul 4 |
| Carrots | Sow outdoors (fall) | May 11 – Jun 26 |
| Garlic | Plant outdoors (fall) | Sep 10 – Oct 11 |
Where these dates come from
ZIP code 82435 is matched to the NOAA station Powell Fld Stn, WY, 2.7 km away, at 4,372 ft elevation (44 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Powell Fld Stn, WY (used) | 4,372 ft | May 19 | Sep 20 |
| Heart Mtn, WY | 4,790 ft | May 15 | Sep 25 |
| Deaver, WY | 4,105 ft | May 6 | Oct 1 |
| Lovell, WY | 3,847 ft | May 9 | Sep 29 |
Frost dates near Powell
- Ralston, WY 82440 · last May 15, first Sep 25
- Byron, WY 82412 · last May 6, first Oct 1
- Deaver, WY 82421 · last May 6, first Oct 1
- Frannie, WY 82423 · last May 6, first Oct 1
- Cowley, WY 82420 · last May 9, first Sep 29
- Lovell, WY 82431 · last May 9, first Sep 29
- Cody, WY 82414 · last May 17, first Oct 3
- Belfry, MT 59008 · last May 18, first Sep 22
Frequently asked questions
- When is the last frost in Powell, WY?
- For ZIP code 82435, the average last spring frost (32°F) is May 19, based on NOAA 1991-2020 climate normals for the Powell Fld Stn, WY weather station. There is a 1-in-10 chance of a frost after June 4.
- When is the first frost in Powell, WY?
- The average first fall frost (32°F) is September 20. There is a 1-in-10 chance of frost by September 7, so tender plants are at risk from that point on.
- How long is the growing season in 82435?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 123 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.