PoolWindow

Pool season · Wisconsin

Appleton Pool Season: the Year on One Bar

Last updated: July 15, 2026 · dates · water temp

One bar, one year, one Appleton 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.

J F M A M J J A S O N D today (build date)

off-season opening window swim season closing window

Reading it takes ten seconds: 52 dots, one per week. Solid teal is Appleton's swim season; the hollow teal run before it (May 7 to May 28) is when to open; the hollow amber run after is when to close, with September 26 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.

The Appleton pool calendar

May 14open by
September 26close by
4580°F+ days
72°Fwater peak

Opening — target May 14

Open by May 14 — a two-week head start on the May 28 crossing keeps startup chemistry small and beats the local service rush.

Full opening guide

Closing — deadline September 26

The window opens September 16 once water leaves the algae zone; the model deadline is September 26, a week ahead of the October 6 freeze normal.

Full closing guide

Where the water sits today

SEASONAL VIEW

Estimated unheated pool water temp (site model, ±5°F). The live estimate loads in your browser from Open-Meteo air temperatures; in a typical year Appleton water runs about 17°F at its winter floor and 72°F at its summer peak.

40 45 50 55 60 65 70 75 80 85 58 open 65 algae

Estimated water temperature by month

This is Appleton'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.

Site-model seasonal water estimates for an unheated in-ground pool near Appleton — ±5°F, see methodology.
JanFebMarAprMayJunJulAugSepOctNovDec
20°18°26°38°51°63°70°71°66°55°42°29°

The curve peaks near 72°F — comfortable-water months here usually involve a heater or a solar cover.

Data: NOAA 1991–2020 climate normals via Appleton (2.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.