Monroe, WI frost dates
Last spring frostApr 27median date
First fall frostOct 14median date
Growing season170 daysfrost-free
Hardiness zone5aZone 5a
How Monroe compares
- In 8 years out of 10, the last spring frost in Monroe falls between April 12 and May 12, a 30-day window. The first fall frost falls between September 29 and October 29.
- The median last frost is 8 days earlier than the Wisconsin median of May 5.
- Its 170-day growing season is longer than 86% of the 749 Wisconsin places with a regular frost season (state median 155 days).
- The last frost is 6 days earlier than the zone 5a median of May 3. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5a chart.
- The weather station records an average of 150 nights a year at or below 32°F.
- Compared with Janesville, WI, 50 km away, the last frost here is 1 day later than there and the growing season is 2 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 12 |
| 50% (median) | April 27 |
| 10% (safe for tender plants) | May 12 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 29 |
| 50% (median) | October 14 |
| 90% (late) | October 29 |
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 Monroe, WI
Monroe, WI frost dates — last frost Apr 27, first frost Oct 14, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Feb 2 to Feb 16Transplant outside: Mar 30 to Apr 13
Start indoors: Feb 16 to Mar 2Transplant outside: May 11 to May 25
Start indoors: Feb 16 to Mar 2Transplant outside: May 11 to May 25
Start indoors: Mar 2 to Mar 16Transplant outside: May 4 to May 18
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 6 to Apr 20Sow outdoors: Mar 30 to May 4Plant for fall: Aug 19 to Sep 16
Start indoors: Mar 2 to Mar 16Transplant outside: Mar 30 to Apr 13Sow outdoors: Mar 30 to Apr 13Plant for fall: Aug 5 to Aug 26
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 13 to Apr 27Plant for fall: Jul 8 to Jul 29
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 6 to Apr 20Plant for fall: Jul 8 to Jul 29
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 13 to Apr 27Plant for fall: Jul 8 to Jul 29
Start indoors: Mar 16 to Mar 30Transplant outside: May 18 to Jun 1Sow outdoors: May 18 to Jun 1
Start indoors: Mar 16 to Mar 30Transplant outside: May 4 to May 18
Sow outdoors: Mar 16 to Apr 6Plant for fall: Jul 22 to Aug 12
Sow outdoors: Mar 16 to Apr 6Plant for fall: Aug 19 to Sep 9
Sow outdoors: Mar 23 to May 4Plant for fall: Sep 2 to Sep 23
Start indoors: Mar 30 to Apr 6Transplant outside: May 11 to May 18Sow outdoors: May 4 to May 18Plant for fall: Jul 29 to Aug 12
Start indoors: Mar 30 to Apr 6Sow outdoors: May 4 to May 18Plant for fall: Aug 5 to Aug 19
Start indoors: Mar 30 to Apr 6Sow outdoors: May 4 to May 18
Start indoors: Mar 30 to Apr 6Transplant outside: May 11 to May 25
Sow outdoors: Apr 6 to May 4Plant for fall: Jul 22 to Aug 5
Sow outdoors: Apr 6 to May 4Plant for fall: Aug 5 to Aug 19
Sow outdoors: Apr 6 to Apr 27
Sow outdoors: Apr 13 to May 11Plant for fall: Aug 5 to Aug 19
Sow outdoors: Apr 13 to May 4Plant for fall: Aug 19 to Sep 9
Sow outdoors: May 4 to May 25Plant for fall: Jul 29 to Aug 12
Sow outdoors: May 4 to May 18
Transplant outside: May 11 to Jun 1
Plant for fall: Sep 30 to Nov 4
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Monroe, WI
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 2 – Feb 16 | Mar 30 – Apr 13 | — | — |
| Peppers | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Eggplant | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Tomatoes | Mar 2 – Mar 16 | May 4 – May 18 | — | — |
| Lettuce | Mar 2 – Mar 16 | Apr 6 – Apr 20 | Mar 30 – May 4 | Aug 19 – Sep 16 |
| Kale | Mar 2 – Mar 16 | Mar 30 – Apr 13 | Mar 30 – Apr 13 | Aug 5 – Aug 26 |
| Broccoli | Mar 2 – Mar 16 | Apr 13 – Apr 27 | — | Jul 8 – Jul 29 |
| Cabbage | Mar 2 – Mar 16 | Apr 6 – Apr 20 | — | Jul 8 – Jul 29 |
| Cauliflower | Mar 2 – Mar 16 | Apr 13 – Apr 27 | — | Jul 8 – Jul 29 |
| Okra | Mar 16 – Mar 30 | May 18 – Jun 1 | May 18 – Jun 1 | — |
| Basil | Mar 16 – Mar 30 | May 4 – May 18 | — | — |
| Peas | — | — | Mar 16 – Apr 6 | Jul 22 – Aug 12 |
| Spinach | — | — | Mar 16 – Apr 6 | Aug 19 – Sep 9 |
| Radishes | — | — | Mar 23 – May 4 | Sep 2 – Sep 23 |
| Cucumbers | Mar 30 – Apr 6 | May 11 – May 18 | May 4 – May 18 | Jul 29 – Aug 12 |
| Zucchini & Summer Squash | Mar 30 – Apr 6 | — | May 4 – May 18 | Aug 5 – Aug 19 |
| Winter Squash & Pumpkins | Mar 30 – Apr 6 | — | May 4 – May 18 | — |
| Melons & Watermelon | Mar 30 – Apr 6 | May 11 – May 25 | — | — |
| Carrots | — | — | Apr 6 – May 4 | Jul 22 – Aug 5 |
| Beets | — | — | Apr 6 – May 4 | Aug 5 – Aug 19 |
| Potatoes | — | — | Apr 6 – Apr 27 | — |
| Swiss Chard | — | — | Apr 13 – May 11 | Aug 5 – Aug 19 |
| Cilantro | — | — | Apr 13 – May 4 | Aug 19 – Sep 9 |
| Green Beans | — | — | May 4 – May 25 | Jul 29 – Aug 12 |
| Sweet Corn | — | — | May 4 – May 18 | — |
| Sweet Potatoes | — | May 11 – Jun 1 | — | — |
| Garlic | — | — | — | Sep 30 – Nov 4 |
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 Monroe Wwtp, WI weather station, 2 km away (elevation 991 ft (302 m)).
Frost dates near Monroe
- Juda Apr 29 · Oct 12
- Browntown Apr 27 · Oct 14
- Monticello Apr 27 · Oct 14
- Woodford Apr 27 · Oct 14
- South Wayne Apr 27 · Oct 14
- Argyle Apr 27 · Oct 14
- Albany Apr 29 · Oct 12
- Brodhead Apr 29 · Oct 12
- New Glarus Apr 27 · Oct 14
- Blanchardville May 3 · Oct 4
Frequently asked questions
When is the last frost in Monroe, WI?
The median last spring frost in Monroe, WI is April 27. There is still about a 10% chance of frost after May 12, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Monroe, WI?
The median first fall frost is October 14, with about a 10% chance of frost before September 29.
How long is the growing season in Monroe, WI?
About 170 days between the median last spring frost and first fall frost.
What planting zone is Monroe, WI?
Monroe, WI is in USDA hardiness zone 5a.