Historical weather data, all-time temperature records, and monthly climate averages for Onalaska, WI. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th in Onalaska sits right on the edge of spring's uncertainty — the average high is just 50° with a low around 31°, but the date has swung wildly from 11° in 1995 to a shirt-sleeve 80° as recently as 2021. There's a 36% chance of some precipitation today, with a 1-in-10 shot it still comes down as snow.
Onalaska's climate doesn't mess around at the extremes — the thermometer has reached a scorching 108° in July 1995 and plunged to a brutal -37° in January 1951, a range of 145 degrees. A single August day in 2021 dropped 5.59 inches of rain, and December 1990 buried the area under 14.4 inches of snow in one storm.
Summer is the sweet spot, with highs peaking around 84–85° in mid-July, while mid-January bottoms out at a frigid 24°. June is your wettest month to plan around, averaging over an inch of precipitation in its rainiest week alone. If you're visiting, May through September offers the most comfortable window — anything outside that range comes with a real coat requirement.