Frost dates for 50040Boxholm, IA
The average last spring frost in Boxholm is April 28 and the average first fall frost is October 12, 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 12
- Growing season
- 165 days
Safer after May 11 (1-in-10 risk)
Possible by Sep 28 (1-in-10 risk)
Last frost typically in 183 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 25 · May 7 · May 22 | Sep 20 · Oct 1 · Oct 14 | 145 days | 100% |
| Frost / freeze (32°F) | Apr 13 · Apr 28 · May 11 | Sep 28 · Oct 12 · Oct 25 | 165 days | 100% |
| Hard freeze (28°F) | Apr 3 · Apr 16 · Apr 30 | Oct 8 · Oct 22 · Nov 3 | 187 days | 100% |
Planting calendar for Boxholm
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 22 |
| 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 – Jul 2 |
| Summer squash | Sow outdoors | May 14 – Jun 28 |
| Winter squash & pumpkins | Sow outdoors | May 28 – Jun 28 |
| Snap beans | Sow outdoors | May 14 – Jul 25 |
| Sweet corn | Sow outdoors | May 14 – Jun 22 |
| 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 12 – Jun 22 |
| Broccoli | Transplant outdoors (fall) | Jul 12 – Jul 23 |
| Cabbage | Start seeds indoors (spring) | Feb 28 – Mar 28 |
| Cabbage | Transplant outdoors (spring) | Mar 28 – Apr 28 |
| Cabbage | Start seeds indoors (fall) | Jun 2 – Jul 2 |
| Cabbage | Transplant outdoors (fall) | Jul 2 – Aug 2 |
| Leaf lettuce | Sow outdoors (spring) | Mar 28 – Jun 13 |
| Leaf lettuce | Sow outdoors (fall) | Jul 2 – Aug 18 |
| Spinach | Sow outdoors (spring) | Mar 21 – May 4 |
| Spinach | Sow outdoors (fall) | Jul 19 – Aug 23 |
| Radishes | Sow outdoors (spring) | Mar 28 – May 18 |
| Radishes | Sow outdoors (fall) | Jul 2 – Sep 2 |
| Kale | Sow outdoors (spring) | Apr 14 – May 4 |
| Kale | Sow outdoors (fall) | Jun 25 – Aug 2 |
| Carrots | Sow outdoors (spring) | Apr 28 – Jun 13 |
| Carrots | Sow outdoors (fall) | Jun 2 – Jul 18 |
| Garlic | Plant outdoors (fall) | Oct 2 – Nov 2 |
Where these dates come from
ZIP code 50040 is matched to the NOAA station Boone, IA, 22.8 km away, at 1,035 ft elevation (107 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Boone, IA (used) | 1,035 ft | Apr 28 | Oct 12 |
| Jefferson, IA | 1,055 ft | Apr 26 | Oct 9 |
| Ames 8 Wsw, IA | 1,099 ft | Apr 23 | Oct 14 |
| Perry, IA | 950 ft | Apr 25 | Oct 10 |
Frost dates near Boxholm
- Pilot Mound, IA 50223 · last Apr 28, first Oct 12
- Dayton, IA 50530 · last Apr 28, first Oct 12
- Harcourt, IA 50544 · last Apr 26, first Oct 9
- Dana, IA 50064 · last Apr 26, first Oct 9
- Paton, IA 50217 · last Apr 26, first Oct 9
- Beaver, IA 50031 · last Apr 28, first Oct 12
- Ogden, IA 50212 · last Apr 28, first Oct 12
- Grand Junction, IA 50107 · last Apr 26, first Oct 9
Frequently asked questions
- When is the last frost in Boxholm, IA?
- For ZIP code 50040, the average last spring frost (32°F) is April 28, based on NOAA 1991-2020 climate normals for the Boone, IA weather station. There is a 1-in-10 chance of a frost after May 11.
- When is the first frost in Boxholm, IA?
- The average first fall frost (32°F) is October 12. There is a 1-in-10 chance of frost by September 28, so tender plants are at risk from that point on.
- How long is the growing season in 50040?
- 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.