Fort Atkinson, WI frost dates
Last spring frostApr 28median date
First fall frostOct 13median date
Growing season168 daysfrost-free
Hardiness zone5bZone 5b
How Fort Atkinson compares
- In 8 years out of 10, the last spring frost in Fort Atkinson falls between April 14 and May 17, a 33-day window. The first fall frost falls between September 29 and October 26.
- The median last frost is 7 days earlier than the Wisconsin median of May 5.
- Its 168-day growing season is longer than 83% of the 749 Wisconsin places with a regular frost season (state median 155 days).
- The last frost is typical for zone 5b, where the median is May 1.
- The weather station records an average of 146 nights a year at or below 32°F.
- Compared with Janesville, WI, 29 km away, the last frost here is 2 days later than there and the growing season is 4 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 14 |
| 50% (median) | April 28 |
| 10% (safe for tender plants) | May 17 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 29 |
| 50% (median) | October 13 |
| 90% (late) | October 26 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Fort Atkinson, WI
Fort Atkinson, WI frost dates — last frost Apr 28, first frost Oct 13, zone 5b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 3 to Feb 17Transplant outside: Mar 31 to Apr 14
Start indoors: Feb 17 to Mar 3Transplant outside: May 12 to May 26
Start indoors: Feb 17 to Mar 3Transplant outside: May 12 to May 26
Start indoors: Mar 3 to Mar 17Transplant outside: May 5 to May 19
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 7 to Apr 21Sow outdoors: Mar 31 to May 5Plant for fall: Aug 18 to Sep 15
Start indoors: Mar 3 to Mar 17Transplant outside: Mar 31 to Apr 14Sow outdoors: Mar 31 to Apr 14Plant for fall: Aug 4 to Aug 25
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 14 to Apr 28Plant for fall: Jul 7 to Jul 28
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 7 to Apr 21Plant for fall: Jul 7 to Jul 28
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 14 to Apr 28Plant for fall: Jul 7 to Jul 28
Start indoors: Mar 17 to Mar 31Transplant outside: May 19 to Jun 2Sow outdoors: May 19 to Jun 2
Start indoors: Mar 17 to Mar 31Transplant outside: May 5 to May 19
Sow outdoors: Mar 17 to Apr 7Plant for fall: Jul 21 to Aug 11
Sow outdoors: Mar 17 to Apr 7Plant for fall: Aug 18 to Sep 8
Sow outdoors: Mar 24 to May 5Plant for fall: Sep 1 to Sep 22
Start indoors: Mar 31 to Apr 7Transplant outside: May 12 to May 19Sow outdoors: May 5 to May 19Plant for fall: Jul 28 to Aug 11
Start indoors: Mar 31 to Apr 7Sow outdoors: May 5 to May 19Plant for fall: Aug 4 to Aug 18
Start indoors: Mar 31 to Apr 7Sow outdoors: May 5 to May 19
Start indoors: Mar 31 to Apr 7Transplant outside: May 12 to May 26
Sow outdoors: Apr 7 to May 5Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 7 to May 5Plant for fall: Aug 4 to Aug 18
Sow outdoors: Apr 7 to Apr 28
Sow outdoors: Apr 14 to May 12Plant for fall: Aug 4 to Aug 18
Sow outdoors: Apr 14 to May 5Plant for fall: Aug 18 to Sep 8
Sow outdoors: May 5 to May 26Plant for fall: Jul 28 to Aug 11
Sow outdoors: May 5 to May 19
Transplant outside: May 12 to Jun 2
Plant for fall: Sep 29 to Nov 3
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Fort Atkinson, WI
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 3 – Feb 17 | Mar 31 – Apr 14 | — | — |
| Peppers | Feb 17 – Mar 3 | May 12 – May 26 | — | — |
| Eggplant | Feb 17 – Mar 3 | May 12 – May 26 | — | — |
| Tomatoes | Mar 3 – Mar 17 | May 5 – May 19 | — | — |
| Lettuce | Mar 3 – Mar 17 | Apr 7 – Apr 21 | Mar 31 – May 5 | Aug 18 – Sep 15 |
| Kale | Mar 3 – Mar 17 | Mar 31 – Apr 14 | Mar 31 – Apr 14 | Aug 4 – Aug 25 |
| Broccoli | Mar 3 – Mar 17 | Apr 14 – Apr 28 | — | Jul 7 – Jul 28 |
| Cabbage | Mar 3 – Mar 17 | Apr 7 – Apr 21 | — | Jul 7 – Jul 28 |
| Cauliflower | Mar 3 – Mar 17 | Apr 14 – Apr 28 | — | Jul 7 – Jul 28 |
| Okra | Mar 17 – Mar 31 | May 19 – Jun 2 | May 19 – Jun 2 | — |
| Basil | Mar 17 – Mar 31 | May 5 – May 19 | — | — |
| Peas | — | — | Mar 17 – Apr 7 | Jul 21 – Aug 11 |
| Spinach | — | — | Mar 17 – Apr 7 | Aug 18 – Sep 8 |
| Radishes | — | — | Mar 24 – May 5 | Sep 1 – Sep 22 |
| Cucumbers | Mar 31 – Apr 7 | May 12 – May 19 | May 5 – May 19 | Jul 28 – Aug 11 |
| Zucchini & Summer Squash | Mar 31 – Apr 7 | — | May 5 – May 19 | Aug 4 – Aug 18 |
| Winter Squash & Pumpkins | Mar 31 – Apr 7 | — | May 5 – May 19 | — |
| Melons & Watermelon | Mar 31 – Apr 7 | May 12 – May 26 | — | — |
| Carrots | — | — | Apr 7 – May 5 | Jul 21 – Aug 4 |
| Beets | — | — | Apr 7 – May 5 | Aug 4 – Aug 18 |
| Potatoes | — | — | Apr 7 – Apr 28 | — |
| Swiss Chard | — | — | Apr 14 – May 12 | Aug 4 – Aug 18 |
| Cilantro | — | — | Apr 14 – May 5 | Aug 18 – Sep 8 |
| Green Beans | — | — | May 5 – May 26 | Jul 28 – Aug 11 |
| Sweet Corn | — | — | May 5 – May 19 | — |
| Sweet Potatoes | — | May 12 – Jun 2 | — | — |
| Garlic | — | — | — | Sep 29 – Nov 3 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Ft Atkinson, WI weather station, 2 km away (elevation 801 ft (244 m)).
Frost dates near Fort Atkinson
- Jefferson Apr 25 · Oct 18
- Whitewater May 2 · Oct 9
- Cambridge Apr 29 · Oct 14
- Helenville Apr 25 · Oct 18
- Johnson Creek Apr 25 · Oct 18
- Milton Apr 28 · Oct 13
- Lake Mills Apr 29 · Oct 14
- Edgerton Apr 30 · Oct 11
- Palmyra May 3 · Oct 9
- Sullivan May 3 · Oct 9
Frequently asked questions
When is the last frost in Fort Atkinson, WI?
The median last spring frost in Fort Atkinson, WI is April 28. There is still about a 10% chance of frost after May 17, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Fort Atkinson, WI?
The median first fall frost is October 13, with about a 10% chance of frost before September 29.
How long is the growing season in Fort Atkinson, WI?
About 168 days between the median last spring frost and first fall frost.
What planting zone is Fort Atkinson, WI?
Fort Atkinson, WI is in USDA hardiness zone 5b.