Frost dates for 82620Alcova, WY
The average last spring frost in Alcova is May 9 and the average first fall frost is October 7, giving a typical growing season of about 148 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 9
- Average first fall frost
- Oct 7
- Growing season
- 148 days
Safer after May 23 (1-in-10 risk)
Possible by Sep 22 (1-in-10 risk)
Last frost typically in 194 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 9 · May 21 · Jun 3 | Sep 14 · Sep 28 · Oct 12 | 128 days | 100% |
| Frost / freeze (32°F) | Apr 28 · May 9 · May 23 | Sep 22 · Oct 7 · Oct 21 | 148 days | 100% |
| Hard freeze (28°F) | Apr 16 · Apr 30 · May 12 | Sep 30 · Oct 16 · Oct 31 | 167 days | 100% |
Planting calendar for Alcova
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 8 – Jun 14 |
| Tomatoes | Transplant outdoors | May 25 – Jun 17 |
| Peppers | Start seeds indoors | Apr 8 – May 9 |
| Peppers | Transplant outdoors | Jun 8 – Jul 9 |
| Eggplant | Start seeds indoors | Apr 25 – May 24 |
| Eggplant | Transplant outdoors | Jun 8 – Jul 9 |
| Cucumbers | Sow outdoors | Jun 8 – Jun 27 |
| Summer squash | Sow outdoors | May 25 – Jul 9 |
| Winter squash & pumpkins | Sow outdoors | Jun 8 – Jul 9 |
| Snap beans | Sow outdoors | May 25 – Jul 20 |
| Sweet corn | Sow outdoors | May 25 – Jun 17 |
| Watermelon & cantaloupe | Sow outdoors | Jun 8 – Jul 9 |
| Okra | Sow outdoors | Jun 1 – Jun 24 |
| Peas | Sow outdoors (spring) | Apr 8 – May 24 |
| Potatoes | Plant outdoors (spring) | Apr 8 – Jun 8 |
| Onions | Start seeds indoors (spring) | Feb 25 – Mar 24 |
| Onions | Transplant outdoors (spring) | Apr 25 – May 24 |
| Broccoli | Start seeds indoors (spring) | Mar 21 – Apr 24 |
| Broccoli | Transplant outdoors (spring) | Apr 25 – May 24 |
| Broccoli | Start seeds indoors (fall) | Jun 7 – Jun 17 |
| Broccoli | Transplant outdoors (fall) | Jul 7 – Jul 18 |
| Cabbage | Start seeds indoors (spring) | Mar 11 – Apr 8 |
| Cabbage | Transplant outdoors (spring) | Apr 8 – May 9 |
| Cabbage | Start seeds indoors (fall) | May 28 – Jun 27 |
| Cabbage | Transplant outdoors (fall) | Jun 27 – Jul 28 |
| Leaf lettuce | Sow outdoors (spring) | Apr 8 – Jun 24 |
| Leaf lettuce | Sow outdoors (fall) | Jun 27 – Aug 13 |
| Spinach | Sow outdoors (spring) | Apr 1 – May 15 |
| Spinach | Sow outdoors (fall) | Jul 14 – Aug 18 |
| Radishes | Sow outdoors (spring) | Apr 8 – May 29 |
| Radishes | Sow outdoors (fall) | Jun 27 – Aug 28 |
| Kale | Sow outdoors (spring) | Apr 25 – May 15 |
| Kale | Sow outdoors (fall) | Jun 20 – Jul 28 |
| Carrots | Sow outdoors (spring) | May 9 – Jun 24 |
| Carrots | Sow outdoors (fall) | May 28 – Jul 13 |
| Garlic | Plant outdoors (fall) | Sep 27 – Oct 28 |
Where these dates come from
ZIP code 82620 is matched to the NOAA station Pathfinder Dam, WY, 10 km away, at 5,923 ft elevation (421 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Pathfinder Dam, WY (used) | 5,923 ft | May 9 | Oct 7 |
| Bates Creek #2, WY | 6,042 ft | May 22 | Sep 26 |
| Leo 6 Sw, WY | 6,035 ft | May 20 | Sep 28 |
| Seminoe Rsvr Usbr, WY | 6,975 ft | May 12 | Oct 4 |
Frost dates near Alcova
- Casper, WY 82604 · last May 10, first Sep 29
- Mills, WY 82644 · last May 10, first Sep 29
- Natrona, WY 82646 · last May 23, first Sep 20
- Powder River, WY 82648 · last May 30, first Sep 22
- Evansville, WY 82636 · last May 10, first Sep 29
- Bairoil, WY 82322 · last May 21, first Sep 27
- Hanna, WY 82327 · last Jun 1, first Sep 8
- Glenrock, WY 82637 · last May 10, first Sep 29
Frequently asked questions
- When is the last frost in Alcova, WY?
- For ZIP code 82620, the average last spring frost (32°F) is May 9, based on NOAA 1991-2020 climate normals for the Pathfinder Dam, WY weather station. There is a 1-in-10 chance of a frost after May 23.
- When is the first frost in Alcova, WY?
- The average first fall frost (32°F) is October 7. There is a 1-in-10 chance of frost by September 22, so tender plants are at risk from that point on.
- How long is the growing season in 82620?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 148 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.