When to plant in Oconomowoc, WI
USDA Zone 5bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Oconomowoc, Wisconsin — all computed from Oconomowoc's nearest NOAA weather station.
Zone 5b means Oconomowoc sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
OCONOMOWOC WWTP · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Oconomowoc’s own odds, recorded at OCONOMOWOC WWTP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 28 | May 12 | Apr 27 | Sep 20 | Oct 2 | Oct 14 |
| 32°F | May 17 | Apr 30 | Apr 16 | Sep 29 | Oct 12 | Oct 27 |
| 28°F | May 3 | Apr 19 | Apr 5 | Oct 9 | Oct 24 | Nov 5 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Oconomowoc, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 21 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Oconomowoc planting FAQ
When is the last spring frost in Oconomowoc, WI?
On average, the last spring frost in Oconomowoc is around April 30 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Oconomowoc, WI?
The first fall frost in Oconomowoc typically arrives around October 12 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Oconomowoc in?
Oconomowoc is in USDA hardiness zone 5b. In zone 5b, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Oconomowoc?
There are roughly 165 frost-free days in Oconomowoc (a moderate growing season), running from the average last frost around April 30 to the first fall frost near October 12.
When should I plant tomatoes in Oconomowoc?
In Oconomowoc, start tomato seeds indoors around March 5–March 19, then transplant seedlings outdoors around May 7 once the danger of frost has passed.
Never miss a window in Oconomowoc
An email when it’s time to start seeds, transplant, and sow — timed to Oconomowoc’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at OCONOMOWOC WWTP, 1 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Oconomowoc, WI — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00476200. Retrieved from https://blissgarden.com/wisconsin/oconomowoc.