Pool season · Wisconsin
Oshkosh Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Oshkosh 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.
Oshkosh, WI — 52 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Oshkosh's swim season; the hollow teal run before it (May 4 to May 25) is when to open; the hollow amber run after is when to close, with September 30 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Oshkosh pool calendar
Opening — target May 11
Target May 11; the practical window runs May 4–May 25, and the 7-day mean crosses the 61°F threshold around May 25. Cold-water starts are the cheap ones.
Closing — deadline September 30
The window opens September 20 once water leaves the algae zone; the model deadline is September 30, a week ahead of the October 20 freeze normal.
Estimated water temperature by month
This is Oshkosh's typical-year water curve: the same EWMA model as the live widget, run on the 1991–2020 normals instead of this week's weather.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 20° | 19° | 27° | 39° | 52° | 64° | 71° | 72° | 67° | 56° | 43° | 30° |
The curve peaks near 72°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Milwaukee's pool season and Racine's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Wisconsin season index.
Oshkosh pool season FAQ
When should I open my pool in Oshkosh, WI?
Open by May 11 — the model places Oshkosh's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Oshkosh opening guide has the 12-step sequence.
When should I close my pool in Oshkosh?
Close by September 30: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Oshkosh closing guide sequences the work backward from that date.
How long is the swim season in Oshkosh?
Oshkosh averages 52 days a year with normal highs of 80°F or better — right on the statewide median. The Wisconsin season index ranks all 11 covered cities by the same metric.
How warm does pool water get in Oshkosh?
An unheated pool near Oshkosh typically peaks around 72°F in high summer and bottoms out near 18°F in winter, never quite reaching the 78°F comfort line without a heater or solar cover. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Oshkosh hits the closing window
Data: NOAA 1991–2020 climate normals via Oshkosh (0.2 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.