Frost dates for 50067Decatur, IA
The average last spring frost in Decatur is April 16 and the average first fall frost is October 21, giving a typical growing season of about 186 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 16
- Average first fall frost
- Oct 21
- Growing season
- 186 days
Safer after May 2 (1-in-10 risk)
Possible by Oct 6 (1-in-10 risk)
Last frost typically in 165 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 12 · Apr 28 · May 11 | Sep 25 · Oct 10 · Oct 22 | 165 days | 100% |
| Frost / freeze (32°F) | Apr 2 · Apr 16 · May 2 | Oct 6 · Oct 21 · Nov 1 | 186 days | 100% |
| Hard freeze (28°F) | Mar 22 · Apr 6 · Apr 21 | Oct 16 · Oct 30 · Nov 12 | 205 days | 100% |
Planting calendar for Decatur
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 16 – May 22 |
| Tomatoes | Transplant outdoors | May 2 – Jul 1 |
| Peppers | Start seeds indoors | Mar 16 – Apr 16 |
| Peppers | Transplant outdoors | May 16 – Jun 16 |
| Eggplant | Start seeds indoors | Apr 2 – May 1 |
| Eggplant | Transplant outdoors | May 16 – Jun 16 |
| Cucumbers | Sow outdoors | May 16 – Jul 11 |
| Summer squash | Sow outdoors | May 2 – Jun 16 |
| Winter squash & pumpkins | Sow outdoors | May 16 – Jun 16 |
| Snap beans | Sow outdoors | May 2 – Aug 3 |
| Sweet corn | Sow outdoors | May 2 – Jul 1 |
| Watermelon & cantaloupe | Sow outdoors | May 16 – Jun 16 |
| Okra | Sow outdoors | May 9 – Jun 1 |
| Peas | Sow outdoors (spring) | Mar 16 – May 1 |
| Potatoes | Plant outdoors (spring) | Mar 16 – May 16 |
| Onions | Start seeds indoors (spring) | Feb 2 – Mar 1 |
| Onions | Transplant outdoors (spring) | Apr 2 – May 1 |
| Broccoli | Start seeds indoors (spring) | Feb 26 – Apr 1 |
| Broccoli | Transplant outdoors (spring) | Apr 2 – May 1 |
| Broccoli | Start seeds indoors (fall) | Jun 21 – Jul 1 |
| Broccoli | Transplant outdoors (fall) | Jul 21 – Aug 1 |
| Cabbage | Start seeds indoors (spring) | Feb 16 – Mar 16 |
| Cabbage | Transplant outdoors (spring) | Mar 16 – Apr 16 |
| Cabbage | Start seeds indoors (fall) | Jun 11 – Jul 11 |
| Cabbage | Transplant outdoors (fall) | Jul 11 – Aug 11 |
| Leaf lettuce | Sow outdoors (spring) | Mar 16 – Jun 1 |
| Leaf lettuce | Sow outdoors (fall) | Jul 11 – Aug 27 |
| Spinach | Sow outdoors (spring) | Mar 9 – Apr 22 |
| Spinach | Sow outdoors (fall) | Jul 28 – Sep 1 |
| Radishes | Sow outdoors (spring) | Mar 16 – May 6 |
| Radishes | Sow outdoors (fall) | Jul 11 – Sep 11 |
| Kale | Sow outdoors (spring) | Apr 2 – Apr 22 |
| Kale | Sow outdoors (fall) | Jul 4 – Aug 11 |
| Carrots | Sow outdoors (spring) | Apr 16 – Jun 1 |
| Carrots | Sow outdoors (fall) | Jun 11 – Jul 27 |
| Garlic | Plant outdoors (fall) | Oct 11 – Nov 11 |
Where these dates come from
ZIP code 50067 is matched to the NOAA station Lamoni Muni Ap, IA, 13.6 km away, at 1,131 ft elevation (15 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Lamoni Muni Ap, IA (used) | 1,131 ft | Apr 16 | Oct 21 |
| Leon 6 Ese, IA | 1,000 ft | Apr 30 | Oct 8 |
| Lamoni, IA | 1,128 ft | Apr 17 | Oct 21 |
| Lamoni, IA | 1,168 ft | Apr 16 | Oct 20 |
Frost dates near Decatur
- Leon, IA 50144 · last Apr 30, first Oct 8
- Davis City, IA 50065 · last Apr 16, first Oct 21
- Grand River, IA 50108 · last Apr 23, first Oct 17
- Van Wert, IA 50262 · last Apr 29, first Oct 9
- Lamoni, IA 50140 · last Apr 17, first Oct 21
- Weldon, IA 50264 · last Apr 29, first Oct 9
- Garden Grove, IA 50103 · last Apr 30, first Oct 8
- Kellerton, IA 50133 · last Apr 17, first Oct 21
Frequently asked questions
- When is the last frost in Decatur, IA?
- For ZIP code 50067, the average last spring frost (32°F) is April 16, based on NOAA 1991-2020 climate normals for the Lamoni Muni Ap, IA weather station. There is a 1-in-10 chance of a frost after May 2.
- When is the first frost in Decatur, IA?
- The average first fall frost (32°F) is October 21. There is a 1-in-10 chance of frost by October 6, so tender plants are at risk from that point on.
- How long is the growing season in 50067?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 186 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.