Frost dates for 51010Castana, IA
The average last spring frost in Castana is May 3 and the average first fall frost is October 1, giving a typical growing season of about 151 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 3
- Average first fall frost
- Oct 1
- Growing season
- 151 days
Safer after May 16 (1-in-10 risk)
Possible by Sep 19 (1-in-10 risk)
Last frost typically in 188 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 29 · May 11 · May 24 | Sep 11 · Sep 24 · Oct 6 | 137 days | 100% |
| Frost / freeze (32°F) | Apr 21 · May 3 · May 16 | Sep 19 · Oct 1 · Oct 17 | 151 days | 100% |
| Hard freeze (28°F) | Apr 10 · Apr 24 · May 6 | Sep 27 · Oct 12 · Oct 26 | 170 days | 100% |
Planting calendar for Castana
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 | Apr 2 – Jun 8 |
| Tomatoes | Transplant outdoors | May 19 – Jun 11 |
| Peppers | Start seeds indoors | Apr 2 – May 3 |
| Peppers | Transplant outdoors | Jun 2 – Jul 3 |
| Eggplant | Start seeds indoors | Apr 19 – May 18 |
| Eggplant | Transplant outdoors | Jun 2 – Jul 3 |
| Cucumbers | Sow outdoors | Jun 2 – Jun 21 |
| Summer squash | Sow outdoors | May 19 – Jul 3 |
| Winter squash & pumpkins | Sow outdoors | Jun 2 – Jul 3 |
| Snap beans | Sow outdoors | May 19 – Jul 14 |
| Sweet corn | Sow outdoors | May 19 – Jun 11 |
| Watermelon & cantaloupe | Sow outdoors | Jun 2 – Jul 3 |
| Okra | Sow outdoors | May 26 – Jun 18 |
| Peas | Sow outdoors (spring) | Apr 2 – May 18 |
| Potatoes | Plant outdoors (spring) | Apr 2 – Jun 2 |
| Onions | Start seeds indoors (spring) | Feb 19 – Mar 18 |
| Onions | Transplant outdoors (spring) | Apr 19 – May 18 |
| Broccoli | Start seeds indoors (spring) | Mar 15 – Apr 18 |
| Broccoli | Transplant outdoors (spring) | Apr 19 – May 18 |
| Broccoli | Start seeds indoors (fall) | Jun 1 – Jun 11 |
| Broccoli | Transplant outdoors (fall) | Jul 1 – Jul 12 |
| Cabbage | Start seeds indoors (spring) | Mar 5 – Apr 2 |
| Cabbage | Transplant outdoors (spring) | Apr 2 – May 3 |
| Cabbage | Start seeds indoors (fall) | May 22 – Jun 21 |
| Cabbage | Transplant outdoors (fall) | Jun 21 – Jul 22 |
| Leaf lettuce | Sow outdoors (spring) | Apr 2 – Jun 18 |
| Leaf lettuce | Sow outdoors (fall) | Jun 21 – Aug 7 |
| Spinach | Sow outdoors (spring) | Mar 26 – May 9 |
| Spinach | Sow outdoors (fall) | Jul 8 – Aug 12 |
| Radishes | Sow outdoors (spring) | Apr 2 – May 23 |
| Radishes | Sow outdoors (fall) | Jun 21 – Aug 22 |
| Kale | Sow outdoors (spring) | Apr 19 – May 9 |
| Kale | Sow outdoors (fall) | Jun 14 – Jul 22 |
| Carrots | Sow outdoors (spring) | May 3 – Jun 18 |
| Carrots | Sow outdoors (fall) | May 22 – Jul 7 |
| Garlic | Plant outdoors (fall) | Sep 21 – Oct 22 |
Where these dates come from
ZIP code 51010 is matched to the NOAA station Mapleton No.2, IA, 14.2 km away, at 1,200 ft elevation (55 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Mapleton No.2, IA (used) | 1,200 ft | May 3 | Oct 1 |
| Castana Exp Farm, IA | 1,400 ft | Apr 25 | Oct 12 |
| Onawa 3Nw, IA | 1,060 ft | May 1 | Oct 3 |
| Little Sioux 2 Nw, IA | 1,025 ft | May 1 | Oct 3 |
Frost dates near Castana
- Mapleton, IA 51034 · last May 3, first Oct 1
- Soldier, IA 51572 · last Apr 25, first Oct 12
- Rodney, IA 51051 · last May 3, first Oct 1
- Ute, IA 51060 · last May 3, first Oct 1
- Onawa, IA 51040 · last May 1, first Oct 3
- Moorhead, IA 51558 · last May 1, first Oct 3
- Smithland, IA 51056 · last May 3, first Oct 1
- Oto, IA 51044 · last May 3, first Oct 1
Frequently asked questions
- When is the last frost in Castana, IA?
- For ZIP code 51010, the average last spring frost (32°F) is May 3, based on NOAA 1991-2020 climate normals for the Mapleton No.2, IA weather station. There is a 1-in-10 chance of a frost after May 16.
- When is the first frost in Castana, IA?
- The average first fall frost (32°F) is October 1. There is a 1-in-10 chance of frost by September 19, so tender plants are at risk from that point on.
- How long is the growing season in 51010?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 151 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.