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Will it freeze in Oconomowoc in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Fri, Nov 6: 27°F (Fri, Nov 6, 6:00 PM CST to Sat, Nov 7, 6:00 AM CST).
Tonight: forecast low 35°F. Frost possible.
NWS forecast period: Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST.
6 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 35°F Frost possible · Mostly Cloudy
- Fri, Nov 6 27°F Hard freeze · Mostly Clear
- Sat, Nov 7 31°F Freeze · Mostly Clear
- Sun, Nov 8 33°F Frost possible · Clear
- Mon, Nov 9 39°F Above 36°F · Mostly Clear
- Tue, Nov 10 35°F Frost possible · Partly Cloudy
- Wed, Nov 11 36°F Frost possible · Partly Cloudy
Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.
Frost and freeze probabilities
Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.
These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.
Average first hard freeze in Oconomowoc
The median first fall hard-freeze date (28°F) is October 24, from NOAA’s 1991–2020 Climate Normals at Oconomowoc Wastewater Plant. This is the 50% probability date, not a forecast for this year.
| Temperature | Last spring date 90% · 50% · 10% chance of a later freeze | First fall date 10% · 50% · 90% chance of an earlier freeze | Season |
|---|---|---|---|
| 36°F frost possible | Apr 27 · May 12 · May 28 | Sep 20 · Oct 2 · Oct 14 | 142 days |
| 32°F freeze | Apr 16 · Apr 30 · May 17 | Sep 29 · Oct 12 · Oct 27 | 164 days |
| 28°F hard freeze | Apr 5 · Apr 19 · May 3 | Oct 9 · Oct 24 · Nov 5 | 186 days |
Average high temperature by month
1991–2020 normals at Oconomowoc Wastewater Plant
Average low temperature by month
Months with lows near or below freezing carry frost risk
Where these frost dates come from
The frost dates for Oconomowoc, WI come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Oconomowoc Wastewater Plant (station USC00476200, elevation 858 ft), 0.4 mi from Oconomowoc. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.
Frost dates near Oconomowoc
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Summit, WI | 3.7 mi | Apr 30 | Oct 12 |
| Delafield, WI | 5.6 mi | Apr 30 | Oct 12 |
| Hartland, WI | 8.1 mi | May 1 | Oct 13 |
| Pewaukee, WI | 12 mi | Apr 30 | Oct 14 |
| Pewaukee, WI | 13 mi | Apr 30 | Oct 14 |
| Lisbon, WI | 13 mi | Apr 30 | Oct 16 |
| Watertown, WI | 13 mi | Apr 28 | Oct 12 |
| Sussex, WI | 14 mi | Apr 30 | Oct 16 |
| Waukesha, WI | 14 mi | May 1 | Oct 13 |
| Waukesha, WI | 16 mi | May 1 | Oct 13 |
Frequently asked questions
When is the last frost in Oconomowoc?
On average, the last spring frost (32°F) in Oconomowoc is around April 30. In about 1 year in 10 it comes after May 17, and in 9 years in 10 it comes after April 16.
When is the first frost in Oconomowoc?
The first fall frost (32°F) usually arrives around October 12. There’s a 10% chance of a freeze by September 29 and a 90% chance by October 27.
Can it frost in Oconomowoc after the last frost date?
Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after May 12.
What growing zone is Oconomowoc?
Oconomowoc is in USDA Plant Hardiness Zone 5b (average annual extreme minimum temperature −15 to −10°F), based on the 2023 USDA map for ZIP code 53066. See growing zones in Wisconsin.
More: all Wisconsin frost dates · Wisconsin growing zones · frost vs. freeze