Pool season · Wisconsin
Wausau Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
Wausau's whole pool calendar, condensed: when the water warms, when it cools, and where today falls between those edges. Use the opening guide and closing guide for the step-by-step work; keep this page for the dates.
Each dot on the bar is one week of Wausau'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 10–May 31), solid teal is swim season, and hollow amber is the closing window ending September 21. The black marker is today — its position against the colors is the entire executive summary.
The Wausau pool calendar
Opening — target May 17
Open by May 17 — a two-week head start on the May 31 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline September 21
The window opens September 11 once water leaves the algae zone; the model deadline is September 21, a week ahead of the October 4 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Wausau'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 17° | 16° | 25° | 37° | 50° | 62° | 68° | 69° | 64° | 53° | 39° | 26° |
The curve peaks near 70°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Wausau hits the closing window
Data: NOAA 1991–2020 climate normals via Wausau Dwtn Airport (2.7 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.