PoolWindow

Pool season · Wisconsin

Milwaukee Pool Season: the Year on One Bar

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

This is the one-page view of Milwaukee's pool year: both model windows, the estimated water-temperature curve, and today's live position on the season bar. The detailed checklists live on the opening and closing guides; this page is the calendar you check between them.

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

off-season opening window swim season closing window

The bar compresses Milwaukee's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the May 6–May 27 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends October 2. Wherever the today marker sits, the nearest color change is your next appointment.

The Milwaukee pool calendar

May 13open by
October 2close by
6380°F+ days
73°Fwater peak

Opening — target May 13

Open by May 13 — a two-week head start on the May 27 crossing keeps startup chemistry small and beats the local service rush.

Full opening guide

Closing — deadline October 2

The window opens September 22 once water leaves the algae zone; the model deadline is October 2, a week ahead of the October 18 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 Milwaukee water runs about 21°F at its winter floor and 73°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 Milwaukee'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 Mt Mary College — ±5°F, see methodology.
JanFebMarAprMayJunJulAugSepOctNovDec
24°22°31°41°53°63°72°72°68°57°44°32°

The curve peaks near 73°F — comfortable-water months here usually involve a heater or a solar cover.

Data: NOAA 1991–2020 climate normals via Mt Mary College (3.2 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.