Pool season · Wisconsin
Green Bay Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one Green Bay pool. The season bar below draws everything the model knows — opening window, prime season, closing window — against today's date, with the working details one click away on the opening and closing pages.
Each dot on the bar is one week of Green Bay's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (May 11–June 1), solid teal is swim season, and hollow amber is the closing window ending September 23. The black marker is today — its position against the colors is the entire executive summary.
The Green Bay pool calendar
Opening — target May 18
Open by May 18 — a two-week head start on the June 1 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline September 23
Hold the cover until September 13, then winterize by September 23, a week ahead of the October 9 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Green Bay's own normals — the shape of a typical year, not a forecast. The widget above shows where the current year actually sits.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 19° | 17° | 26° | 38° | 50° | 61° | 68° | 69° | 64° | 54° | 42° | 29° |
The curve peaks near 70°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Green Bay hits the closing window
Data: NOAA 1991–2020 climate normals via Green Bay Botanical (5.5 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.