Frost Dates for Gillette, WY
In Gillette, WY, the average last spring frost is around May 15 and the average first fall frost around Oct 1, for a growing season of about 136 days. For frost-tender plants, wait until May 27, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Gillette 4Se, WY weather station, 2 miles away, elevation 4,640 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | May 27 | Sep 15 |
| 20% | May 24 | Sep 21 |
| 30% | May 21 | Sep 25 |
| 40% | May 17 | Sep 28 |
| 50% | May 15 | Oct 1 |
| 60% | May 12 | Oct 3 |
| 70% | May 10 | Oct 6 |
| 80% | May 6 | Oct 9 |
| 90% | May 1 | Oct 14 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | May 28 | Sep 21 |
| Frost / freeze (32°F) | May 15 | Oct 1 |
| Hard freeze (28°F) | May 2 | Oct 10 |
Planting calendar for Gillette
Transplant May 22 – Jun 5
Transplant May 29 – Jun 12
Transplant May 29 – Jun 12
Transplant May 22 – Jun 5
Sow or transplant May 22 – Jun 5
Sow or transplant May 22 – Jun 5
Sow or transplant May 29 – Jun 12
Sow or transplant Apr 17 – May 1
Fall sowing Aug 6 – Sep 3
Fall sowing Aug 6 – Aug 27
Fall sowing Jul 23 – Aug 6
Sow or transplant Apr 17 – May 1
Fall sowing Jul 23 – Aug 20
Transplant May 1 – May 15
Fall sowing Jul 9 – Jul 23
Transplant Apr 24 – May 8
Fall sowing Jul 9 – Jul 23
Fall sowing Jul 9 – Jul 23
Fall sowing Aug 20 – Sep 10
Fall sowing Jul 23 – Aug 6
Plant Apr 17 – May 1
Based on the average last frost (May 15) and first frost (Oct 1). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.