Frost dates for 80729Grover, CO
The average last spring frost in Grover is May 18 and the average first fall frost is September 29, giving a typical growing season of about 133 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 18
- Average first fall frost
- Sep 29
- Growing season
- 133 days
Safer after Jun 2 (1-in-10 risk)
Possible by Sep 15 (1-in-10 risk)
Last frost typically in 203 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 15 · May 28 · Jun 13 | Sep 6 · Sep 21 · Oct 2 | 114 days | 100% |
| Frost / freeze (32°F) | May 5 · May 18 · Jun 2 | Sep 15 · Sep 29 · Oct 11 | 133 days | 100% |
| Hard freeze (28°F) | Apr 22 · May 6 · May 22 | Sep 25 · Oct 8 · Oct 19 | 153 days | 100% |
Planting calendar for Grover
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 17 – Jun 23 |
| Tomatoes | Transplant outdoors | Jun 3 – Jun 9 |
| Peppers | Start seeds indoors | Apr 17 – May 18 |
| Peppers | Transplant outdoors | Jun 17 – Jul 18 |
| Eggplant | Start seeds indoors | May 4 – Jun 2 |
| Eggplant | Transplant outdoors | Jun 17 – Jul 18 |
| Cucumbers | Sow outdoors | Jun 17 – Jun 19 |
| Summer squash | Sow outdoors | Jun 3 – Jul 18 |
| Winter squash & pumpkins | Sow outdoors | Jun 17 – Jul 18 |
| Snap beans | Sow outdoors | Jun 3 – Jul 12 |
| Sweet corn | Sow outdoors | Jun 3 – Jun 9 |
| Watermelon & cantaloupe | Sow outdoors | Jun 17 – Jul 18 |
| Okra | Sow outdoors | Jun 10 – Jul 3 |
| Peas | Sow outdoors (spring) | Apr 17 – Jun 2 |
| Potatoes | Plant outdoors (spring) | Apr 17 – Jun 17 |
| Onions | Start seeds indoors (spring) | Mar 6 – Apr 2 |
| Onions | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (spring) | Mar 30 – May 3 |
| Broccoli | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (fall) | May 30 – Jun 9 |
| Broccoli | Transplant outdoors (fall) | Jun 29 – Jul 10 |
| Cabbage | Start seeds indoors (spring) | Mar 20 – Apr 17 |
| Cabbage | Transplant outdoors (spring) | Apr 17 – May 18 |
| Cabbage | Start seeds indoors (fall) | May 20 – Jun 19 |
| Cabbage | Transplant outdoors (fall) | Jun 19 – Jul 20 |
| Leaf lettuce | Sow outdoors (spring) | Apr 17 – Jul 3 |
| Leaf lettuce | Sow outdoors (fall) | Jun 19 – Aug 5 |
| Spinach | Sow outdoors (spring) | Apr 10 – May 24 |
| Spinach | Sow outdoors (fall) | Jul 6 – Aug 10 |
| Radishes | Sow outdoors (spring) | Apr 17 – Jun 7 |
| Radishes | Sow outdoors (fall) | Jun 19 – Aug 20 |
| Kale | Sow outdoors (spring) | May 4 – May 24 |
| Kale | Sow outdoors (fall) | Jun 12 – Jul 20 |
| Carrots | Sow outdoors (spring) | May 18 – Jul 3 |
| Carrots | Sow outdoors (fall) | May 20 – Jul 5 |
| Garlic | Plant outdoors (fall) | Sep 19 – Oct 20 |
Where these dates come from
ZIP code 80729 is matched to the NOAA station New Raymer 21 N, CO, 31.5 km away, at 5,180 ft elevation (95 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| New Raymer 21 N, CO (used) | 5,180 ft | May 18 | Sep 29 |
| Carpenter 3N, WY | 5,437 ft | May 14 | Sep 26 |
| Briggsdale, CO | 4,862 ft | May 12 | Sep 28 |
| Bushnell 15S, NE | 5,170 ft | May 25 | Sep 21 |
Frost dates near Grover
- Hereford, CO 80732 · last May 16, first Sep 27
- Carpenter, WY 82054 · last May 16, first Sep 27
- Briggsdale, CO 80611 · last May 12, first Sep 28
- Pine Bluffs, WY 82082 · last May 16, first Sep 27
- Burns, WY 82053 · last May 16, first Sep 27
- New Raymer, CO 80742 · last May 9, first Oct 4
- Galeton, CO 80622 · last May 12, first Sep 28
- Hillsdale, WY 82060 · last May 14, first Sep 26
Frequently asked questions
- When is the last frost in Grover, CO?
- For ZIP code 80729, the average last spring frost (32°F) is May 18, based on NOAA 1991-2020 climate normals for the New Raymer 21 N, CO weather station. There is a 1-in-10 chance of a frost after June 2.
- When is the first frost in Grover, CO?
- The average first fall frost (32°F) is September 29. 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 80729?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 133 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.