Frost dates for 50434Fertile, IA
The average last spring frost in Fertile is May 3 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 3
- Average first fall frost
- Oct 1
- Growing season
- 150 days
Safer after May 15 (1-in-10 risk)
Possible by Sep 18 (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 30 · May 11 · May 25 | Sep 10 · Sep 24 · Oct 5 | 134 days | 100% |
| Frost / freeze (32°F) | Apr 19 · May 3 · May 15 | Sep 18 · Oct 1 · Oct 15 | 150 days | 100% |
| Hard freeze (28°F) | Apr 9 · Apr 24 · May 7 | Sep 27 · Oct 11 · Oct 23 | 169 days | 100% |
Planting calendar for Fertile
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 50434 is matched to the NOAA station Mason City Muni Ap, IA, 14.3 km away, at 1,225 ft elevation (54 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Mason City Muni Ap, IA (used) | 1,225 ft | May 3 | Oct 1 |
| Forest City 2 Nne, IA | 1,280 ft | Apr 30 | Oct 7 |
| Mason City, IA | 1,105 ft | Apr 29 | Oct 7 |
| Northwood, IA | 1,190 ft | May 4 | Oct 4 |
Frost dates near Fertile
- Hanlontown, IA 50444 · last May 3, first Oct 1
- Joice, IA 50446 · last Apr 30, first Oct 7
- Clear Lake, IA 50428 · last May 3, first Oct 1
- Ventura, IA 50482 · last May 3, first Oct 1
- Forest City, IA 50436 · last Apr 30, first Oct 7
- Manly, IA 50456 · last May 4, first Oct 4
- Lake Mills, IA 50450 · last Apr 30, first Oct 7
- Kensett, IA 50448 · last May 4, first Oct 4
Frequently asked questions
- When is the last frost in Fertile, IA?
- For ZIP code 50434, the average last spring frost (32°F) is May 3, based on NOAA 1991-2020 climate normals for the Mason City Muni Ap, IA weather station. There is a 1-in-10 chance of a frost after May 15.
- When is the first frost in Fertile, 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 50434?
- 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.