Last frost date in Oconomowoc, WI
The average last frost in Oconomowoc is April 30. By May 17 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about October 12, which leaves 164 frost-free days. An early freeze before September 29 happens one year in ten.
- Safe after (10% risk)
- May 17
- Average first frost
- Oct 12
- Frost-free season
- 164 days
- Hard freeze (28°F) ends
- Apr 19
No frost in the next 7 nights
Later than usual: the average first frost here is October 12.
National Weather Service forecast, updated Oct 22, 12:57 UTC
- ThuOct 2248°
- FriOct 2349°
- SatOct 2452°
- SunOct 2549°
- MonOct 2644°
- TueOct 2742°
- WedOct 2843°
Planting calendar for Oconomowoc
Windows count forward or back from the average frost dates above. Click a crop for dates across Wisconsin.
TomatoesMay 7–May 21
PumpkinsMay 14–May 28
SunflowersApr 30–May 21
CucumbersMay 14–May 21
CornMay 7–May 21
Sweet potatoesMay 21–Jun 4
WatermelonMay 14–May 28
Green beansMay 7–May 28
ZucchiniMay 7–May 21
OkraMay 21–Jun 4
PeppersMay 14–May 28
BasilMay 7–May 21
Butternut squashMay 7–May 21
CantaloupeMay 14–May 28
EggplantMay 14–May 28
PotatoesApr 2–Apr 16
OnionsMar 19–Apr 9
CarrotsApr 9–May 14
LettuceApr 16–May 7
BroccoliApr 2–Apr 16
BeetsApr 2–May 14
PeasMar 19–Apr 2
CabbageApr 2–Apr 16
RadishesMar 26–May 7
Brussels sproutsApr 16–Apr 30
SpinachMar 19–Apr 9
CilantroApr 16–May 7
KaleApr 2–Apr 16
Collard greensApr 2–Apr 16
TurnipsApr 2–Apr 16
DillApr 30–May 14
CeleryMay 7–May 14
CauliflowerApr 16–Apr 30
LeeksApr 16–Apr 30
Swiss chardApr 16–May 14
ParsleyApr 16–May 7
Tulip bulbsSep 28–Nov 2
GarlicSep 21–Oct 26
Daffodil bulbsSep 14–Oct 26
StrawberriesApr 2–Apr 16
AsparagusApr 2–Apr 16Frost probabilities
| Threshold | Spring, 90% chance later | Spring, 50% | Spring, 10% | Fall, 10% chance earlier | Fall, 50% | Fall, 90% |
|---|---|---|---|---|---|---|
| Light frost, 32°F | Apr 16 | Apr 30 | May 17 | Sep 29 | Oct 12 | Oct 27 |
| Hard freeze, 28°F | Apr 5 | Apr 19 | May 3 | Oct 9 | Oct 24 | Nov 5 |
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 Oconomowoc Wwtp (USC00476200) sits 0.4 miles from the center of Oconomowoc at 858 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 Oconomowoc, WI?
The average last frost date in Oconomowoc is April 30, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 17.
When is the first frost in Oconomowoc?
The first frost in fall usually comes around October 12. One year in ten it arrives before September 29.
How long is the growing season in Oconomowoc?
About 164 days between the average last and first frost.
When should I plant tomatoes in Oconomowoc?
Plant tomato seedlings outside from May 7 to May 21. Start seeds indoors six to eight weeks earlier.
Nearby in Wisconsin
- WatertownApr 28
- WaukeshaMay 1
- BrookfieldApr 30
- Menomonee FallsMay 6
- New BerlinMay 3
- GermantownMay 6
- WauwatosaApr 26
- MuskegoMay 3
- West AllisApr 26
- MequonMay 6
- GreenfieldMay 3
- MilwaukeeApr 26