Frost dates for 50517Bancroft, IA
The average last spring frost in Bancroft is May 4 and the average first fall frost is October 1, giving a typical growing season of about 150 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 4
- Average first fall frost
- Oct 1
- Growing season
- 150 days
Safer after May 14 (1-in-10 risk)
Possible by Sep 18 (1-in-10 risk)
Last frost typically in 189 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) | May 1 · May 11 · May 24 | Sep 11 · Sep 23 · Oct 6 | 134 days | 100% |
| Frost / freeze (32°F) | Apr 21 · May 4 · May 14 | Sep 18 · Oct 1 · Oct 15 | 150 days | 100% |
| Hard freeze (28°F) | Apr 9 · Apr 25 · May 6 | Sep 26 · Oct 10 · Oct 24 | 168 days | 100% |
Planting calendar for Bancroft
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 3 – Jun 9 |
| Tomatoes | Transplant outdoors | May 20 – Jun 11 |
| Peppers | Start seeds indoors | Apr 3 – May 4 |
| Peppers | Transplant outdoors | Jun 3 – Jul 4 |
| Eggplant | Start seeds indoors | Apr 20 – May 19 |
| Eggplant | Transplant outdoors | Jun 3 – Jul 4 |
| Cucumbers | Sow outdoors | Jun 3 – Jun 21 |
| Summer squash | Sow outdoors | May 20 – Jul 4 |
| Winter squash & pumpkins | Sow outdoors | Jun 3 – Jul 4 |
| Snap beans | Sow outdoors | May 20 – Jul 14 |
| Sweet corn | Sow outdoors | May 20 – Jun 11 |
| Watermelon & cantaloupe | Sow outdoors | Jun 3 – Jul 4 |
| Okra | Sow outdoors | May 27 – Jun 19 |
| Peas | Sow outdoors (spring) | Apr 3 – May 19 |
| Potatoes | Plant outdoors (spring) | Apr 3 – Jun 3 |
| Onions | Start seeds indoors (spring) | Feb 20 – Mar 19 |
| Onions | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (spring) | Mar 16 – Apr 19 |
| Broccoli | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (fall) | Jun 1 – Jun 11 |
| Broccoli | Transplant outdoors (fall) | Jul 1 – Jul 12 |
| Cabbage | Start seeds indoors (spring) | Mar 6 – Apr 3 |
| Cabbage | Transplant outdoors (spring) | Apr 3 – May 4 |
| Cabbage | Start seeds indoors (fall) | May 22 – Jun 21 |
| Cabbage | Transplant outdoors (fall) | Jun 21 – Jul 22 |
| Leaf lettuce | Sow outdoors (spring) | Apr 3 – Jun 19 |
| Leaf lettuce | Sow outdoors (fall) | Jun 21 – Aug 7 |
| Spinach | Sow outdoors (spring) | Mar 27 – May 10 |
| Spinach | Sow outdoors (fall) | Jul 8 – Aug 12 |
| Radishes | Sow outdoors (spring) | Apr 3 – May 24 |
| Radishes | Sow outdoors (fall) | Jun 21 – Aug 22 |
| Kale | Sow outdoors (spring) | Apr 20 – May 10 |
| Kale | Sow outdoors (fall) | Jun 14 – Jul 22 |
| Carrots | Sow outdoors (spring) | May 4 – Jun 19 |
| Carrots | Sow outdoors (fall) | May 22 – Jul 7 |
| Garlic | Plant outdoors (fall) | Sep 21 – Oct 22 |
Where these dates come from
ZIP code 50517 is matched to the NOAA station Swea City 5N, IA, 19.5 km away, at 1,180 ft elevation (19 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Swea City 5N, IA (used) | 1,180 ft | May 4 | Oct 1 |
| Algona, IA | 1,214 ft | Apr 30 | Oct 6 |
| Britt 3E, IA | 1,220 ft | Apr 29 | Oct 7 |
| Emmetsburg, IA | 1,225 ft | Apr 27 | Oct 7 |
Frost dates near Bancroft
- Burt, IA 50522 · last Apr 30, first Oct 6
- Lakota, IA 50451 · last May 4, first Oct 1
- Swea City, IA 50590 · last May 4, first Oct 1
- Titonka, IA 50480 · last Apr 30, first Oct 6
- Ledyard, IA 50556 · last May 4, first Oct 1
- Fenton, IA 50539 · last Apr 30, first Oct 6
- Lone Rock, IA 50559 · last Apr 30, first Oct 6
- Buffalo Center, IA 50424 · last Apr 30, first Oct 7
Frequently asked questions
- When is the last frost in Bancroft, IA?
- For ZIP code 50517, the average last spring frost (32°F) is May 4, based on NOAA 1991-2020 climate normals for the Swea City 5N, IA weather station. There is a 1-in-10 chance of a frost after May 14.
- When is the first frost in Bancroft, IA?
- The average first fall frost (32°F) is October 1. There is a 1-in-10 chance of frost by September 18, so tender plants are at risk from that point on.
- How long is the growing season in 50517?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 150 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.