Frost dates for 82717Gillette, WY
The average last spring frost in Gillette is May 15 and the average first fall frost is October 1, giving a typical growing season of about 136 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 15
- Average first fall frost
- Oct 1
- Growing season
- 136 days
Safer after May 27 (1-in-10 risk)
Possible by Sep 15 (1-in-10 risk)
Last frost typically in 200 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 14 · May 28 · Jun 12 | Sep 6 · Sep 21 · Oct 3 | 114 days | 100% |
| Frost / freeze (32°F) | May 1 · May 15 · May 27 | Sep 15 · Oct 1 · Oct 14 | 136 days | 100% |
| Hard freeze (28°F) | Apr 18 · May 2 · May 15 | Sep 26 · Oct 10 · Oct 23 | 159 days | 100% |
Planting calendar for Gillette
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 14 – Jun 20 |
| Tomatoes | Transplant outdoors | May 31 – Jun 11 |
| Peppers | Start seeds indoors | Apr 14 – May 15 |
| Peppers | Transplant outdoors | Jun 14 – Jul 15 |
| Eggplant | Start seeds indoors | May 1 – May 30 |
| Eggplant | Transplant outdoors | Jun 14 – Jul 15 |
| Cucumbers | Sow outdoors | Jun 14 – Jun 21 |
| Summer squash | Sow outdoors | May 31 – Jul 15 |
| Winter squash & pumpkins | Sow outdoors | Jun 14 – Jul 15 |
| Snap beans | Sow outdoors | May 31 – Jul 14 |
| Sweet corn | Sow outdoors | May 31 – Jun 11 |
| Watermelon & cantaloupe | Sow outdoors | Jun 14 – Jul 15 |
| Okra | Sow outdoors | Jun 7 – Jun 30 |
| Peas | Sow outdoors (spring) | Apr 14 – May 30 |
| Potatoes | Plant outdoors (spring) | Apr 14 – Jun 14 |
| Onions | Start seeds indoors (spring) | Mar 3 – Mar 30 |
| Onions | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (spring) | Mar 27 – Apr 30 |
| Broccoli | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (fall) | Jun 1 – Jun 11 |
| Broccoli | Transplant outdoors (fall) | Jul 1 – Jul 12 |
| Cabbage | Start seeds indoors (spring) | Mar 17 – Apr 14 |
| Cabbage | Transplant outdoors (spring) | Apr 14 – May 15 |
| Cabbage | Start seeds indoors (fall) | May 22 – Jun 21 |
| Cabbage | Transplant outdoors (fall) | Jun 21 – Jul 22 |
| Leaf lettuce | Sow outdoors (spring) | Apr 14 – Jun 30 |
| Leaf lettuce | Sow outdoors (fall) | Jun 21 – Aug 7 |
| Spinach | Sow outdoors (spring) | Apr 7 – May 21 |
| Spinach | Sow outdoors (fall) | Jul 8 – Aug 12 |
| Radishes | Sow outdoors (spring) | Apr 14 – Jun 4 |
| Radishes | Sow outdoors (fall) | Jun 21 – Aug 22 |
| Kale | Sow outdoors (spring) | May 1 – May 21 |
| Kale | Sow outdoors (fall) | Jun 14 – Jul 22 |
| Carrots | Sow outdoors (spring) | May 15 – Jun 30 |
| Carrots | Sow outdoors (fall) | May 22 – Jul 7 |
| Garlic | Plant outdoors (fall) | Sep 21 – Oct 22 |
Where these dates come from
ZIP code 82717 is matched to the NOAA station Gillette 4Se, WY, 5.6 km away, at 4,640 ft elevation (99 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Gillette 4Se, WY (used) | 4,640 ft | May 15 | Oct 1 |
| Gillette Campbell Ap, WY | 4,354 ft | May 22 | Sep 25 |
| Echeta 2 Nw, WY | 4,000 ft | May 21 | Sep 23 |
| Dillinger, WY | 4,310 ft | May 25 | Sep 17 |
Frost dates near Gillette
- Gillette, WY 82716 · last May 15, first Oct 1
- Rozet, WY 82727 · last May 22, first Sep 25
- Weston, WY 82731 · last May 23, first Sep 18
- Moorcroft, WY 82721 · last May 21, first Sep 25
- Recluse, WY 82725 · last May 21, first Sep 23
- Wright, WY 82732 · last May 25, first Sep 23
- Arvada, WY 82831 · last May 21, first Sep 23
- Devils Tower, WY 82714 · last May 23, first Sep 20
Frequently asked questions
- When is the last frost in Gillette, WY?
- For ZIP code 82717, the average last spring frost (32°F) is May 15, based on NOAA 1991-2020 climate normals for the Gillette 4Se, WY weather station. There is a 1-in-10 chance of a frost after May 27.
- When is the first frost in Gillette, WY?
- The average first fall frost (32°F) is October 1. There is a 1-in-10 chance of frost by September 15, so tender plants are at risk from that point on.
- How long is the growing season in 82717?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 136 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.