Frost dates for 52215Chelsea, IA
The average last spring frost in Chelsea is April 28 and the average first fall frost is October 10, giving a typical growing season of about 165 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 28
- Average first fall frost
- Oct 10
- Growing season
- 165 days
Safer after May 11 (1-in-10 risk)
Possible by Sep 26 (1-in-10 risk)
Last frost typically in 176 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) | Apr 24 · May 6 · May 20 | Sep 17 · Oct 1 · Oct 13 | 147 days | 100% |
| Frost / freeze (32°F) | Apr 14 · Apr 28 · May 11 | Sep 26 · Oct 10 · Oct 23 | 165 days | 100% |
| Hard freeze (28°F) | Apr 2 · Apr 16 · May 2 | Oct 5 · Oct 21 · Nov 1 | 185 days | 100% |
Planting calendar for Chelsea
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 | Mar 28 – Jun 3 |
| Tomatoes | Transplant outdoors | May 14 – Jun 20 |
| Peppers | Start seeds indoors | Mar 28 – Apr 28 |
| Peppers | Transplant outdoors | May 28 – Jun 28 |
| Eggplant | Start seeds indoors | Apr 14 – May 13 |
| Eggplant | Transplant outdoors | May 28 – Jun 28 |
| Cucumbers | Sow outdoors | May 28 – Jun 30 |
| Summer squash | Sow outdoors | May 14 – Jun 28 |
| Winter squash & pumpkins | Sow outdoors | May 28 – Jun 28 |
| Snap beans | Sow outdoors | May 14 – Jul 23 |
| Sweet corn | Sow outdoors | May 14 – Jun 20 |
| Watermelon & cantaloupe | Sow outdoors | May 28 – Jun 28 |
| Okra | Sow outdoors | May 21 – Jun 13 |
| Peas | Sow outdoors (spring) | Mar 28 – May 13 |
| Potatoes | Plant outdoors (spring) | Mar 28 – May 28 |
| Onions | Start seeds indoors (spring) | Feb 14 – Mar 13 |
| Onions | Transplant outdoors (spring) | Apr 14 – May 13 |
| Broccoli | Start seeds indoors (spring) | Mar 10 – Apr 13 |
| Broccoli | Transplant outdoors (spring) | Apr 14 – May 13 |
| Broccoli | Start seeds indoors (fall) | Jun 10 – Jun 20 |
| Broccoli | Transplant outdoors (fall) | Jul 10 – Jul 21 |
| Cabbage | Start seeds indoors (spring) | Feb 28 – Mar 28 |
| Cabbage | Transplant outdoors (spring) | Mar 28 – Apr 28 |
| Cabbage | Start seeds indoors (fall) | May 31 – Jun 30 |
| Cabbage | Transplant outdoors (fall) | Jun 30 – Jul 31 |
| Leaf lettuce | Sow outdoors (spring) | Mar 28 – Jun 13 |
| Leaf lettuce | Sow outdoors (fall) | Jun 30 – Aug 16 |
| Spinach | Sow outdoors (spring) | Mar 21 – May 4 |
| Spinach | Sow outdoors (fall) | Jul 17 – Aug 21 |
| Radishes | Sow outdoors (spring) | Mar 28 – May 18 |
| Radishes | Sow outdoors (fall) | Jun 30 – Aug 31 |
| Kale | Sow outdoors (spring) | Apr 14 – May 4 |
| Kale | Sow outdoors (fall) | Jun 23 – Jul 31 |
| Carrots | Sow outdoors (spring) | Apr 28 – Jun 13 |
| Carrots | Sow outdoors (fall) | May 31 – Jul 16 |
| Garlic | Plant outdoors (fall) | Sep 30 – Oct 31 |
Where these dates come from
ZIP code 52215 is matched to the NOAA station Belle Plaine, IA, 11.4 km away, at 810 ft elevation (26 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Belle Plaine, IA (used) | 810 ft | Apr 28 | Oct 10 |
| Toledo 3N, IA | 935 ft | Apr 30 | Oct 9 |
| Grinnell 3 Sw, IA | 905 ft | May 3 | Oct 6 |
| Vinton, IA | 850 ft | May 3 | Oct 3 |
Frost dates near Chelsea
- Vining, IA 52348 · last Apr 28, first Oct 10
- Elberon, IA 52225 · last Apr 28, first Oct 10
- Hartwick, IA 52232 · last Apr 28, first Oct 10
- Belle Plaine, IA 52208 · last Apr 28, first Oct 10
- Tama, IA 52339 · last Apr 30, first Oct 9
- Toledo, IA 52342 · last Apr 30, first Oct 9
- Clutier, IA 52217 · last Apr 30, first Oct 9
- Luzerne, IA 52257 · last Apr 28, first Oct 10
Frequently asked questions
- When is the last frost in Chelsea, IA?
- For ZIP code 52215, the average last spring frost (32°F) is April 28, based on NOAA 1991-2020 climate normals for the Belle Plaine, IA weather station. There is a 1-in-10 chance of a frost after May 11.
- When is the first frost in Chelsea, IA?
- The average first fall frost (32°F) is October 10. There is a 1-in-10 chance of frost by September 26, so tender plants are at risk from that point on.
- How long is the growing season in 52215?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 165 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.