Frost dates for 51401Carroll, IA
The average last spring frost in Carroll is April 27 and the average first fall frost is October 10, giving a typical growing season of about 166 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 27
- Average first fall frost
- Oct 10
- Growing season
- 166 days
Safer after May 8 (1-in-10 risk)
Possible by Sep 25 (1-in-10 risk)
Last frost typically in 182 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 23 · May 6 · May 17 | Sep 17 · Sep 30 · Oct 14 | 147 days | 100% |
| Frost / freeze (32°F) | Apr 14 · Apr 27 · May 8 | Sep 25 · Oct 10 · Oct 24 | 166 days | 100% |
| Hard freeze (28°F) | Apr 3 · Apr 16 · Apr 29 | Oct 5 · Oct 21 · Nov 3 | 187 days | 100% |
Planting calendar for Carroll
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 27 – Jun 2 |
| Tomatoes | Transplant outdoors | May 13 – Jun 20 |
| Peppers | Start seeds indoors | Mar 27 – Apr 27 |
| Peppers | Transplant outdoors | May 27 – Jun 27 |
| Eggplant | Start seeds indoors | Apr 13 – May 12 |
| Eggplant | Transplant outdoors | May 27 – Jun 27 |
| Cucumbers | Sow outdoors | May 27 – Jun 30 |
| Summer squash | Sow outdoors | May 13 – Jun 27 |
| Winter squash & pumpkins | Sow outdoors | May 27 – Jun 27 |
| Snap beans | Sow outdoors | May 13 – Jul 23 |
| Sweet corn | Sow outdoors | May 13 – Jun 20 |
| Watermelon & cantaloupe | Sow outdoors | May 27 – Jun 27 |
| Okra | Sow outdoors | May 20 – Jun 12 |
| Peas | Sow outdoors (spring) | Mar 27 – May 12 |
| Potatoes | Plant outdoors (spring) | Mar 27 – May 27 |
| Onions | Start seeds indoors (spring) | Feb 13 – Mar 12 |
| Onions | Transplant outdoors (spring) | Apr 13 – May 12 |
| Broccoli | Start seeds indoors (spring) | Mar 9 – Apr 12 |
| Broccoli | Transplant outdoors (spring) | Apr 13 – May 12 |
| Broccoli | Start seeds indoors (fall) | Jun 10 – Jun 20 |
| Broccoli | Transplant outdoors (fall) | Jul 10 – Jul 21 |
| Cabbage | Start seeds indoors (spring) | Feb 27 – Mar 27 |
| Cabbage | Transplant outdoors (spring) | Mar 27 – Apr 27 |
| Cabbage | Start seeds indoors (fall) | May 31 – Jun 30 |
| Cabbage | Transplant outdoors (fall) | Jun 30 – Jul 31 |
| Leaf lettuce | Sow outdoors (spring) | Mar 27 – Jun 12 |
| Leaf lettuce | Sow outdoors (fall) | Jun 30 – Aug 16 |
| Spinach | Sow outdoors (spring) | Mar 20 – May 3 |
| Spinach | Sow outdoors (fall) | Jul 17 – Aug 21 |
| Radishes | Sow outdoors (spring) | Mar 27 – May 17 |
| Radishes | Sow outdoors (fall) | Jun 30 – Aug 31 |
| Kale | Sow outdoors (spring) | Apr 13 – May 3 |
| Kale | Sow outdoors (fall) | Jun 23 – Jul 31 |
| Carrots | Sow outdoors (spring) | Apr 27 – Jun 12 |
| Carrots | Sow outdoors (fall) | May 31 – Jul 16 |
| Garlic | Plant outdoors (fall) | Sep 30 – Oct 31 |
Where these dates come from
ZIP code 51401 is matched to the NOAA station Carroll, IA, 1.6 km away, at 1,240 ft elevation (59 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Carroll, IA (used) | 1,240 ft | Apr 27 | Oct 10 |
| Denison, IA | 1,401 ft | Apr 27 | Oct 11 |
| Jefferson, IA | 1,055 ft | Apr 26 | Oct 9 |
| Sac City, IA | 1,210 ft | Apr 30 | Oct 6 |
Frost dates near Carroll
- Lidderdale, IA 51452 · last Apr 27, first Oct 10
- Halbur, IA 51444 · last Apr 27, first Oct 10
- Glidden, IA 51443 · last Apr 27, first Oct 10
- Arcadia, IA 51430 · last Apr 27, first Oct 10
- Breda, IA 51436 · last Apr 27, first Oct 10
- Templeton, IA 51463 · last Apr 27, first Oct 10
- Dedham, IA 51440 · last Apr 27, first Oct 10
- Lanesboro, IA 51451 · last Apr 27, first Oct 10
Frequently asked questions
- When is the last frost in Carroll, IA?
- For ZIP code 51401, the average last spring frost (32°F) is April 27, based on NOAA 1991-2020 climate normals for the Carroll, IA weather station. There is a 1-in-10 chance of a frost after May 8.
- When is the first frost in Carroll, IA?
- The average first fall frost (32°F) is October 10. There is a 1-in-10 chance of frost by September 25, so tender plants are at risk from that point on.
- How long is the growing season in 51401?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 166 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.