Frost dates for 80512Bellvue, CO
The average last spring frost in Bellvue is May 21 and the average first fall frost is September 29, giving a typical growing season of about 128 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 21
- Average first fall frost
- Sep 29
- Growing season
- 128 days
Safer after Jun 4 (1-in-10 risk)
Possible by Sep 12 (1-in-10 risk)
Last frost typically in 206 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 18 · Jun 1 · Jun 15 | Sep 6 · Sep 21 · Oct 3 | 110 days | 100% |
| Frost / freeze (32°F) | May 9 · May 21 · Jun 4 | Sep 12 · Sep 29 · Oct 12 | 128 days | 100% |
| Hard freeze (28°F) | Apr 29 · May 11 · May 26 | Sep 22 · Oct 6 · Oct 22 | 146 days | 100% |
Planting calendar for Bellvue
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 20 – Jun 26 |
| Tomatoes | Transplant outdoors | Jun 6 – Jun 9 |
| Peppers | Start seeds indoors | Apr 20 – May 21 |
| Peppers | Transplant outdoors | Jun 20 – Jul 21 |
| Eggplant | Start seeds indoors | May 7 – Jun 5 |
| Eggplant | Transplant outdoors | Jun 20 – Jul 21 |
| Cucumbers | Sow outdoors | Jun 20 – Jun 19 |
| Summer squash | Sow outdoors | Jun 6 – Jul 21 |
| Winter squash & pumpkins | Sow outdoors | Jun 20 – Jul 21 |
| Snap beans | Sow outdoors | Jun 6 – Jul 12 |
| Sweet corn | Sow outdoors | Jun 6 – Jun 9 |
| Watermelon & cantaloupe | Sow outdoors | Jun 20 – Jul 21 |
| Okra | Sow outdoors | Jun 13 – Jul 6 |
| Peas | Sow outdoors (spring) | Apr 20 – Jun 5 |
| Potatoes | Plant outdoors (spring) | Apr 20 – Jun 20 |
| Onions | Start seeds indoors (spring) | Mar 9 – Apr 5 |
| Onions | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (spring) | Apr 2 – May 6 |
| Broccoli | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (fall) | May 30 – Jun 9 |
| Broccoli | Transplant outdoors (fall) | Jun 29 – Jul 10 |
| Cabbage | Start seeds indoors (spring) | Mar 23 – Apr 20 |
| Cabbage | Transplant outdoors (spring) | Apr 20 – May 21 |
| Cabbage | Start seeds indoors (fall) | May 20 – Jun 19 |
| Cabbage | Transplant outdoors (fall) | Jun 19 – Jul 20 |
| Leaf lettuce | Sow outdoors (spring) | Apr 20 – Jul 6 |
| Leaf lettuce | Sow outdoors (fall) | Jun 19 – Aug 5 |
| Spinach | Sow outdoors (spring) | Apr 13 – May 27 |
| Spinach | Sow outdoors (fall) | Jul 6 – Aug 10 |
| Radishes | Sow outdoors (spring) | Apr 20 – Jun 10 |
| Radishes | Sow outdoors (fall) | Jun 19 – Aug 20 |
| Kale | Sow outdoors (spring) | May 7 – May 27 |
| Kale | Sow outdoors (fall) | Jun 12 – Jul 20 |
| Carrots | Sow outdoors (spring) | May 21 – Jul 6 |
| Carrots | Sow outdoors (fall) | May 20 – Jul 5 |
| Garlic | Plant outdoors (fall) | Sep 19 – Oct 20 |
Where these dates come from
ZIP code 80512 is matched to the NOAA station Buckhorn Mtn 1 E, CO, 3.3 km away, at 7,400 ft elevation (753 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Buckhorn Mtn 1 E, CO (used) | 7,400 ft | May 21 | Sep 29 |
| Ft Collins, CO | 5,004 ft | May 2 | Oct 7 |
| Ft Collins 4 E, CO | 4,920 ft | May 3 | Oct 6 |
| Waterdale, CO | 5,230 ft | May 12 | Oct 1 |
Frost dates near Bellvue
- Laporte, CO 80535 · last May 2, first Oct 7
- Fort Collins, CO 80521 · last May 2, first Oct 7
- Masonville, CO 80541 · last May 12, first Oct 1
- Wellington, CO 80549 · last May 2, first Oct 7
- Drake, CO 80515 · last May 30, first Sep 17
- Glen Haven, CO 80532 · last May 30, first Sep 17
- Timnath, CO 80547 · last May 3, first Oct 6
- Estes Park, CO 80511 · last —, first —
Frequently asked questions
- When is the last frost in Bellvue, CO?
- For ZIP code 80512, the average last spring frost (32°F) is May 21, based on NOAA 1991-2020 climate normals for the Buckhorn Mtn 1 E, CO weather station. There is a 1-in-10 chance of a frost after June 4.
- When is the first frost in Bellvue, CO?
- The average first fall frost (32°F) is September 29. There is a 1-in-10 chance of frost by September 12, so tender plants are at risk from that point on.
- How long is the growing season in 80512?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 128 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.