Frost dates for 82839Ranchester, WY
The average last spring frost in Ranchester is May 24 and the average first fall frost is September 18, giving a typical growing season of about 114 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 24
- Average first fall frost
- Sep 18
- Growing season
- 114 days
Safer after Jun 7 (1-in-10 risk)
Possible by Sep 2 (1-in-10 risk)
Last frost typically in 202 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 24 · Jun 7 · Jun 22 | Aug 23 · Sep 7 · Sep 21 | 89 days | 100% |
| Frost / freeze (32°F) | May 11 · May 24 · Jun 7 | Sep 2 · Sep 18 · Oct 2 | 114 days | 100% |
| Hard freeze (28°F) | Apr 28 · May 9 · May 23 | Sep 13 · Sep 28 · Oct 15 | 140 days | 100% |
Planting calendar for Ranchester
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 23 – Jun 29 |
| Tomatoes | Transplant outdoors | Jun 9 – May 29 |
| Peppers | Start seeds indoors | Apr 23 – May 24 |
| Peppers | Transplant outdoors | Jun 23 – Jul 24 |
| Eggplant | Start seeds indoors | May 10 – Jun 8 |
| Eggplant | Transplant outdoors | Jun 23 – Jul 24 |
| Cucumbers | Sow outdoors | Jun 23 – Jun 8 |
| Summer squash | Sow outdoors | Jun 9 – Jul 24 |
| Winter squash & pumpkins | Sow outdoors | Jun 23 – Jul 24 |
| Snap beans | Sow outdoors | Jun 9 – Jul 1 |
| Sweet corn | Sow outdoors | Jun 9 – May 29 |
| Watermelon & cantaloupe | Sow outdoors | Jun 23 – Jul 24 |
| Okra | Sow outdoors | Jun 16 – Jul 9 |
| Peas | Sow outdoors (spring) | Apr 23 – Jun 8 |
| Potatoes | Plant outdoors (spring) | Apr 23 – Jun 23 |
| Onions | Start seeds indoors (spring) | Mar 12 – Apr 8 |
| Onions | Transplant outdoors (spring) | May 10 – Jun 8 |
| Broccoli | Start seeds indoors (spring) | Apr 5 – May 9 |
| Broccoli | Transplant outdoors (spring) | May 10 – Jun 8 |
| Broccoli | Start seeds indoors (fall) | May 19 – May 29 |
| Broccoli | Transplant outdoors (fall) | Jun 18 – Jun 29 |
| Cabbage | Start seeds indoors (spring) | Mar 26 – Apr 23 |
| Cabbage | Transplant outdoors (spring) | Apr 23 – May 24 |
| Cabbage | Start seeds indoors (fall) | May 9 – Jun 8 |
| Cabbage | Transplant outdoors (fall) | Jun 8 – Jul 9 |
| Leaf lettuce | Sow outdoors (spring) | Apr 23 – Jul 9 |
| Leaf lettuce | Sow outdoors (fall) | Jun 8 – Jul 25 |
| Spinach | Sow outdoors (spring) | Apr 16 – May 30 |
| Spinach | Sow outdoors (fall) | Jun 25 – Jul 30 |
| Radishes | Sow outdoors (spring) | Apr 23 – Jun 13 |
| Radishes | Sow outdoors (fall) | Jun 8 – Aug 9 |
| Kale | Sow outdoors (spring) | May 10 – May 30 |
| Kale | Sow outdoors (fall) | Jun 1 – Jul 9 |
| Carrots | Sow outdoors (spring) | May 24 – Jul 9 |
| Carrots | Sow outdoors (fall) | May 9 – Jun 24 |
| Garlic | Plant outdoors (fall) | Sep 8 – Oct 9 |
Where these dates come from
ZIP code 82839 is matched to the NOAA station Dayton, WY, 8.3 km away, at 3,920 ft elevation (78 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Dayton, WY (used) | 3,920 ft | May 24 | Sep 18 |
| Sheridan Co Ap, WY | 3,945 ft | May 21 | Sep 23 |
| Sheridan Fld Stn, WY | 3,750 ft | May 18 | Sep 24 |
| Big Horn, WY | 4,208 ft | May 17 | Sep 28 |
Frost dates near Ranchester
- Dayton, WY 82836 · last May 24, first Sep 18
- Parkman, WY 82838 · last May 24, first Sep 18
- Wolf, WY 82844 · last May 21, first Sep 23
- Sheridan, WY 82801 · last May 21, first Sep 23
- Wyola, MT 59089 · last May 21, first Sep 17
- Big Horn, WY 82833 · last May 17, first Sep 28
- Decker, MT 59025 · last May 21, first Sep 23
- Wyarno, WY 82845 · last May 21, first Sep 23
Frequently asked questions
- When is the last frost in Ranchester, WY?
- For ZIP code 82839, the average last spring frost (32°F) is May 24, based on NOAA 1991-2020 climate normals for the Dayton, WY weather station. There is a 1-in-10 chance of a frost after June 7.
- When is the first frost in Ranchester, WY?
- The average first fall frost (32°F) is September 18. There is a 1-in-10 chance of frost by September 2, so tender plants are at risk from that point on.
- How long is the growing season in 82839?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 114 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.