Frost dates for 50117Hamlin, IA
The average last spring frost in Hamlin is May 2 and the average first fall frost is October 3, giving a typical growing season of about 154 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 2
- Average first fall frost
- Oct 3
- Growing season
- 154 days
Safer after May 15 (1-in-10 risk)
Possible by Sep 19 (1-in-10 risk)
Last frost typically in 181 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 28 · May 10 · May 23 | Sep 12 · Sep 25 · Oct 8 | 137 days | 100% |
| Frost / freeze (32°F) | Apr 19 · May 2 · May 15 | Sep 19 · Oct 3 · Oct 17 | 154 days | 100% |
| Hard freeze (28°F) | Apr 8 · Apr 22 · May 5 | Sep 28 · Oct 14 · Oct 26 | 173 days | 100% |
Planting calendar for Hamlin
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 1 – Jun 7 |
| Tomatoes | Transplant outdoors | May 18 – Jun 13 |
| Peppers | Start seeds indoors | Apr 1 – May 2 |
| Peppers | Transplant outdoors | Jun 1 – Jul 2 |
| Eggplant | Start seeds indoors | Apr 18 – May 17 |
| Eggplant | Transplant outdoors | Jun 1 – Jul 2 |
| Cucumbers | Sow outdoors | Jun 1 – Jun 23 |
| Summer squash | Sow outdoors | May 18 – Jul 2 |
| Winter squash & pumpkins | Sow outdoors | Jun 1 – Jul 2 |
| Snap beans | Sow outdoors | May 18 – Jul 16 |
| Sweet corn | Sow outdoors | May 18 – Jun 13 |
| Watermelon & cantaloupe | Sow outdoors | Jun 1 – Jul 2 |
| Okra | Sow outdoors | May 25 – Jun 17 |
| Peas | Sow outdoors (spring) | Apr 1 – May 17 |
| Potatoes | Plant outdoors (spring) | Apr 1 – Jun 1 |
| Onions | Start seeds indoors (spring) | Feb 18 – Mar 17 |
| Onions | Transplant outdoors (spring) | Apr 18 – May 17 |
| Broccoli | Start seeds indoors (spring) | Mar 14 – Apr 17 |
| Broccoli | Transplant outdoors (spring) | Apr 18 – May 17 |
| Broccoli | Start seeds indoors (fall) | Jun 3 – Jun 13 |
| Broccoli | Transplant outdoors (fall) | Jul 3 – Jul 14 |
| Cabbage | Start seeds indoors (spring) | Mar 4 – Apr 1 |
| Cabbage | Transplant outdoors (spring) | Apr 1 – May 2 |
| Cabbage | Start seeds indoors (fall) | May 24 – Jun 23 |
| Cabbage | Transplant outdoors (fall) | Jun 23 – Jul 24 |
| Leaf lettuce | Sow outdoors (spring) | Apr 1 – Jun 17 |
| Leaf lettuce | Sow outdoors (fall) | Jun 23 – Aug 9 |
| Spinach | Sow outdoors (spring) | Mar 25 – May 8 |
| Spinach | Sow outdoors (fall) | Jul 10 – Aug 14 |
| Radishes | Sow outdoors (spring) | Apr 1 – May 22 |
| Radishes | Sow outdoors (fall) | Jun 23 – Aug 24 |
| Kale | Sow outdoors (spring) | Apr 18 – May 8 |
| Kale | Sow outdoors (fall) | Jun 16 – Jul 24 |
| Carrots | Sow outdoors (spring) | May 2 – Jun 17 |
| Carrots | Sow outdoors (fall) | May 24 – Jul 9 |
| Garlic | Plant outdoors (fall) | Sep 23 – Oct 24 |
Where these dates come from
ZIP code 50117 is matched to the NOAA station Audubon, IA, 6.3 km away, at 1,280 ft elevation (98 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Audubon, IA (used) | 1,280 ft | May 2 | Oct 3 |
| Atlantic 1 Ne, IA | 1,152 ft | Apr 30 | Oct 2 |
| Harlan, IA | 1,270 ft | Apr 27 | Oct 9 |
| Guthrie Ctr, IA | 1,065 ft | May 2 | Oct 3 |
Frost dates near Hamlin
- Audubon, IA 50025 · last May 2, first Oct 3
- Exira, IA 50076 · last May 2, first Oct 3
- Kimballton, IA 51543 · last May 2, first Oct 3
- Brayton, IA 50042 · last May 2, first Oct 3
- Elk Horn, IA 51531 · last May 2, first Oct 3
- Gray, IA 50110 · last May 2, first Oct 3
- Anita, IA 50020 · last Apr 30, first Oct 2
- Marne, IA 51552 · last Apr 30, first Oct 2
Frequently asked questions
- When is the last frost in Hamlin, IA?
- For ZIP code 50117, the average last spring frost (32°F) is May 2, based on NOAA 1991-2020 climate normals for the Audubon, IA weather station. There is a 1-in-10 chance of a frost after May 15.
- When is the first frost in Hamlin, IA?
- The average first fall frost (32°F) is October 3. 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 50117?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 154 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.