Frost dates for 53538Fort Atkinson, WI
The average last spring frost in Fort Atkinson is April 28 and the average first fall frost is October 13, giving a typical growing season of about 166 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 28
- Average first fall frost
- Oct 13
- Growing season
- 166 days
Safer after May 17 (1-in-10 risk)
Possible by Sep 29 (1-in-10 risk)
Last frost typically in 176 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 10 · May 26 | Sep 20 · Oct 2 · Oct 14 | 145 days | 100% |
| Frost / freeze (32°F) | Apr 14 · Apr 28 · May 17 | Sep 29 · Oct 13 · Oct 26 | 166 days | 100% |
| Hard freeze (28°F) | Apr 3 · Apr 16 · May 3 | Oct 7 · Oct 24 · Nov 6 | 189 days | 100% |
Planting calendar for Fort Atkinson
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 23 |
| 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 3 |
| Summer squash | Sow outdoors | May 14 – Jun 28 |
| Winter squash & pumpkins | Sow outdoors | May 28 – Jun 28 |
| Snap beans | Sow outdoors | May 14 – Jul 26 |
| Sweet corn | Sow outdoors | May 14 – Jun 23 |
| 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 13 – Jun 23 |
| Broccoli | Transplant outdoors (fall) | Jul 13 – Jul 24 |
| Cabbage | Start seeds indoors (spring) | Feb 28 – Mar 28 |
| Cabbage | Transplant outdoors (spring) | Mar 28 – Apr 28 |
| Cabbage | Start seeds indoors (fall) | Jun 3 – Jul 3 |
| Cabbage | Transplant outdoors (fall) | Jul 3 – Aug 3 |
| Leaf lettuce | Sow outdoors (spring) | Mar 28 – Jun 13 |
| Leaf lettuce | Sow outdoors (fall) | Jul 3 – Aug 19 |
| Spinach | Sow outdoors (spring) | Mar 21 – May 4 |
| Spinach | Sow outdoors (fall) | Jul 20 – Aug 24 |
| Radishes | Sow outdoors (spring) | Mar 28 – May 18 |
| Radishes | Sow outdoors (fall) | Jul 3 – Sep 3 |
| Kale | Sow outdoors (spring) | Apr 14 – May 4 |
| Kale | Sow outdoors (fall) | Jun 26 – Aug 3 |
| Carrots | Sow outdoors (spring) | Apr 28 – Jun 13 |
| Carrots | Sow outdoors (fall) | Jun 3 – Jul 19 |
| Garlic | Plant outdoors (fall) | Oct 3 – Nov 3 |
Where these dates come from
ZIP code 53538 is matched to the NOAA station Ft Atkinson, WI, 2.2 km away, at 800 ft elevation (1 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ft Atkinson, WI (used) | 800 ft | Apr 28 | Oct 13 |
| Jefferson Wwtp, WI | 783 ft | Apr 25 | Oct 18 |
| Whitewater, WI | 875 ft | May 2 | Oct 9 |
| Lake Mills Wwtp, WI | 811 ft | Apr 29 | Oct 14 |
Frost dates near Fort Atkinson
- Jefferson, WI 53549 · last Apr 25, first Oct 18
- Whitewater, WI 53190 · last May 2, first Oct 9
- Cambridge, WI 53523 · last Apr 29, first Oct 14
- Helenville, WI 53137 · last Apr 25, first Oct 18
- Johnson Creek, WI 53038 · last Apr 29, first Oct 14
- Milton, WI 53563 · last Apr 28, first Oct 13
- Lake Mills, WI 53551 · last Apr 29, first Oct 14
- Edgerton, WI 53534 · last Apr 30, first Oct 11
Frequently asked questions
- When is the last frost in Fort Atkinson, WI?
- For ZIP code 53538, the average last spring frost (32°F) is April 28, based on NOAA 1991-2020 climate normals for the Ft Atkinson, WI weather station. There is a 1-in-10 chance of a frost after May 17.
- When is the first frost in Fort Atkinson, WI?
- The average first fall frost (32°F) is October 13. There is a 1-in-10 chance of frost by September 29, so tender plants are at risk from that point on.
- How long is the growing season in 53538?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 166 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.