Wisconsin Pool Season: Opening & Closing Dates by City

Local dates for every featured Wisconsin city — when the water warms up, when it cools off, and how long the season actually lasts.

City Opening window Closing window Season
Milwaukee May 25 – Jun 12 Sep 4 – Sep 23 ≈ 105 days
Madison May 28 – Jun 17 Aug 23 – Sep 16 ≈ 90 days
Green Bay Jun 5 – Jul 6 Aug 11 – Sep 8 ≈ 73 days

Windows show the stretch when each city's daily average passes through the low-to-mid 60s°F (1991–2020 NOAA records, nearest station to each city). Click a city for its month-by-month table and full season notes.

Season geography

Across Wisconsin's featured cities, typical openings spread from Jun 3 to Jun 15, closings from Aug 27 to Sep 16, and the unheated season runs 73–105 days depending on where you are. Elevation, coastal water, and urban heat all pull real dates around, which is exactly why a state-level answer isn't enough.

For your exact town, the pool season lookup takes a ZIP code. Opening day itself is a chemistry job — the dosing calculator turns your first test reading of the year into exact amounts.

Wisconsin planning pages

When to open — Wisconsin When to close — Wisconsin All states →