Last frost date in Sun Prairie, WI

Average last frost
May 1

Expect the last frost in Sun Prairie around May 1. Frost after May 16 happens in only one year out of ten. The first fall frost usually arrives about October 10, which leaves 160 frost-free days. An early freeze before September 26 happens one year in ten.

Safe after (10% risk)
May 16
Average first frost
Oct 10
Frost-free season
160 days
Hard freeze (28°F) ends
Apr 20
Next 7 nights in Sun Prairie

No frost in the next 7 nights

Later than usual: the average first frost here is October 10.

National Weather Service forecast, updated Oct 22, 12:57 UTC

  1. ThuOct 2248°
  2. FriOct 2350°
  3. SatOct 2452°
  4. SunOct 2549°
  5. MonOct 2643°
  6. TueOct 2741°
  7. WedOct 2843°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost May 1First frost Oct 10160 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND160 frost-free days
Frost risk through the year at Madison Dane Regional Airport, 6.1 miles from Sun Prairie.

Planting calendar for Sun Prairie

Windows count forward or back from the average frost dates above. Click a crop for dates across Wisconsin.

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesMay 8–May 22
PumpkinsMay 15–May 29
SunflowersMay 1–May 22
CucumbersMay 15–May 22
CornMay 8–May 22
Sweet potatoesMay 22–Jun 5
WatermelonMay 15–May 29
Green beansMay 8–May 29
ZucchiniMay 8–May 22
OkraMay 22–Jun 5
PeppersMay 15–May 29
BasilMay 8–May 22
Butternut squashMay 8–May 22
CantaloupeMay 15–May 29
EggplantMay 15–May 29
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesApr 3–Apr 17
OnionsMar 20–Apr 10
CarrotsApr 10–May 15
LettuceApr 17–May 8
BroccoliApr 3–Apr 17
BeetsApr 3–May 15
PeasMar 20–Apr 3
CabbageApr 3–Apr 17
RadishesMar 27–May 8
Brussels sproutsApr 17–May 1
SpinachMar 20–Apr 10
CilantroApr 17–May 8
KaleApr 3–Apr 17
Collard greensApr 3–Apr 17
TurnipsApr 3–Apr 17
DillMay 1–May 15
CeleryMay 8–May 15
CauliflowerApr 17–May 1
LeeksApr 17–May 1
Swiss chardApr 17–May 15
ParsleyApr 17–May 8
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsSep 26–Oct 31
GarlicSep 19–Oct 24
Daffodil bulbsSep 12–Oct 24
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesApr 3–Apr 17
AsparagusApr 3–Apr 17

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 16May 1May 16Sep 26Oct 10Oct 24
Hard freeze, 28°FApr 5Apr 20May 5Oct 6Oct 22Nov 4

Read the spring 10% column as the date after which only one year in ten still gets frost. That is the safer date for tomatoes, peppers and basil.

Where these numbers come from

NOAA station Madison Dane Regional Airport (USW00014837) sits 6.1 miles from the center of Sun Prairie at 866 feet. Its averages cover 1991 to 2020. Low spots, valleys and open fields can keep getting frost a week or two after the station stops; city centers and lakeshores usually get less of it.

Questions

When is the last frost in Sun Prairie, WI?

The average last frost date in Sun Prairie is May 1, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 16.

When is the first frost in Sun Prairie?

The first frost in fall usually comes around October 10. One year in ten it arrives before September 26.

How long is the growing season in Sun Prairie?

About 160 days between the average last and first frost.

When should I plant tomatoes in Sun Prairie?

Plant tomato seedlings outside from May 8 to May 22. Start seeds indoors six to eight weeks earlier.

Nearby in Wisconsin

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