Frost dates for 52590Seymour, IA
The average last spring frost in Seymour is April 21 and the average first fall frost is October 19, giving a typical growing season of about 178 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 21
- Average first fall frost
- Oct 19
- Growing season
- 178 days
Safer after May 6 (1-in-10 risk)
Possible by Oct 3 (1-in-10 risk)
Last frost typically in 169 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 18 · May 2 · May 17 | Sep 24 · Oct 7 · Oct 20 | 157 days | 100% |
| Frost / freeze (32°F) | Apr 7 · Apr 21 · May 6 | Oct 3 · Oct 19 · Oct 29 | 178 days | 100% |
| Hard freeze (28°F) | Mar 30 · Apr 11 · Apr 25 | Oct 15 · Oct 27 · Nov 7 | 198 days | 100% |
Planting calendar for Seymour
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 21 – May 27 |
| Tomatoes | Transplant outdoors | May 7 – Jun 29 |
| Peppers | Start seeds indoors | Mar 21 – Apr 21 |
| Peppers | Transplant outdoors | May 21 – Jun 21 |
| Eggplant | Start seeds indoors | Apr 7 – May 6 |
| Eggplant | Transplant outdoors | May 21 – Jun 21 |
| Cucumbers | Sow outdoors | May 21 – Jul 9 |
| Summer squash | Sow outdoors | May 7 – Jun 21 |
| Winter squash & pumpkins | Sow outdoors | May 21 – Jun 21 |
| Snap beans | Sow outdoors | May 7 – Aug 1 |
| Sweet corn | Sow outdoors | May 7 – Jun 29 |
| Watermelon & cantaloupe | Sow outdoors | May 21 – Jun 21 |
| Okra | Sow outdoors | May 14 – Jun 6 |
| Peas | Sow outdoors (spring) | Mar 21 – May 6 |
| Potatoes | Plant outdoors (spring) | Mar 21 – May 21 |
| Onions | Start seeds indoors (spring) | Feb 7 – Mar 6 |
| Onions | Transplant outdoors (spring) | Apr 7 – May 6 |
| Broccoli | Start seeds indoors (spring) | Mar 3 – Apr 6 |
| Broccoli | Transplant outdoors (spring) | Apr 7 – May 6 |
| Broccoli | Start seeds indoors (fall) | Jun 19 – Jun 29 |
| Broccoli | Transplant outdoors (fall) | Jul 19 – Jul 30 |
| Cabbage | Start seeds indoors (spring) | Feb 21 – Mar 21 |
| Cabbage | Transplant outdoors (spring) | Mar 21 – Apr 21 |
| Cabbage | Start seeds indoors (fall) | Jun 9 – Jul 9 |
| Cabbage | Transplant outdoors (fall) | Jul 9 – Aug 9 |
| Leaf lettuce | Sow outdoors (spring) | Mar 21 – Jun 6 |
| Leaf lettuce | Sow outdoors (fall) | Jul 9 – Aug 25 |
| Spinach | Sow outdoors (spring) | Mar 14 – Apr 27 |
| Spinach | Sow outdoors (fall) | Jul 26 – Aug 30 |
| Radishes | Sow outdoors (spring) | Mar 21 – May 11 |
| Radishes | Sow outdoors (fall) | Jul 9 – Sep 9 |
| Kale | Sow outdoors (spring) | Apr 7 – Apr 27 |
| Kale | Sow outdoors (fall) | Jul 2 – Aug 9 |
| Carrots | Sow outdoors (spring) | Apr 21 – Jun 6 |
| Carrots | Sow outdoors (fall) | Jun 9 – Jul 25 |
| Garlic | Plant outdoors (fall) | Oct 9 – Nov 9 |
Where these dates come from
ZIP code 52590 is matched to the NOAA station Allerton, IA, 20 km away, at 1,090 ft elevation (17 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Allerton, IA (used) | 1,090 ft | Apr 21 | Oct 19 |
| Centerville, IA | 905 ft | Apr 28 | Oct 14 |
| Unionville, MO | 1,060 ft | Apr 17 | Oct 22 |
| Rathbun Dam, IA | 965 ft | Apr 18 | Oct 23 |
Frost dates near Seymour
- Promise City, IA 52583 · last Apr 18, first Oct 23
- Plano, IA 52581 · last Apr 18, first Oct 23
- Cincinnati, IA 52549 · last Apr 28, first Oct 14
- Powersville, MO 64672 · last Apr 21, first Oct 19
- Corydon, IA 50060 · last Apr 21, first Oct 19
- Allerton, IA 50008 · last Apr 21, first Oct 19
- Mystic, IA 52574 · last Apr 18, first Oct 23
- Centerville, IA 52544 · last Apr 28, first Oct 14
Frequently asked questions
- When is the last frost in Seymour, IA?
- For ZIP code 52590, the average last spring frost (32°F) is April 21, based on NOAA 1991-2020 climate normals for the Allerton, IA weather station. There is a 1-in-10 chance of a frost after May 6.
- When is the first frost in Seymour, IA?
- The average first fall frost (32°F) is October 19. There is a 1-in-10 chance of frost by October 3, so tender plants are at risk from that point on.
- How long is the growing season in 52590?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 178 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.