Lake Koshkonong, WI Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Lake Koshkonong, a community in Rock County, Wisconsin.
This Afternoon
70°F
Chance Rain Showers
A chance of rain showers. Mostly cloudy, with a high near 70. East wind around 15 mph. Chance of precipitation is 40%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast for Lake Koshkonong
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 70°F | Chance Rain Showers | 15 mph E | 35% |
| Tonight | 60°F | Slight Chance Showers And Thunderstorms then Chance Showers And Thunderstorms | 15 mph E | 93% |
| Saturday | 73°F | Showers And Thunderstorms | 10 to 15 mph SE | 93% |
| Saturday Night | 59°F | Showers And Thunderstorms | 10 to 15 mph NE | 76% |
| Sunday | 67°F | Chance Rain Showers | 15 mph NE | 49% |
| Sunday Night | 53°F | Chance Rain Showers then Mostly Cloudy | 15 mph NE | 31% |
| Monday | 62°F | Slight Chance Rain Showers | 15 mph NE | 23% |
| Monday Night | 48°F | Slight Chance Rain Showers | 10 to 15 mph NE | 23% |
| Tuesday | 61°F | Slight Chance Rain Showers then Partly Sunny | 10 to 15 mph NE | 16% |
| Tuesday Night | 47°F | Partly Cloudy | 5 to 10 mph NE | 8% |
| Wednesday | 65°F | Mostly Sunny | 5 to 10 mph NE | 6% |
| Wednesday Night | 48°F | Partly Cloudy | 0 to 5 mph NE | 2% |
| Thursday | 67°F | Mostly Sunny | 0 to 5 mph N | 5% |
| Thursday Night | 50°F | Partly Cloudy | 0 to 5 mph NE | 5% |
Forecast source: National Weather Service (api.weather.gov) for Lake Koshkonong (42.861, -88.940). Updated through the day.
Growing snapshot for Lake Koshkonong
Last spring frost
Apr 28
First fall frost
Oct 13
Growing season
166 days
Hardiness zone
5b
More local growing data for Lake Koshkonong: nearby ZIP 53563 weather · frost dates · planting calendar · Wisconsin frost dates
Nearby towns & communities
Brodhead
Clinton
Edgerton
Evansville
Footville
Fulton
Hanover
Janesville
Milton
Orfordville
Shopiere
Climate data from the nearest NOAA station, Ft Atkinson, Wi (9.4 mi from Lake Koshkonong). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 18, 2026.