Pool season · Illinois
Joliet Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one Joliet 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.
The bar compresses Joliet's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the April 28–May 19 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends October 7. Wherever the today marker sits, the nearest color change is your next appointment.
The Joliet pool calendar
Opening — target May 5
Open by May 5 — a two-week head start on the May 19 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 7
The window opens September 27 once water leaves the algae zone; the model deadline is October 7, a week ahead of the October 25 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Joliet'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 26° | 25° | 33° | 44° | 55° | 66° | 73° | 73° | 70° | 60° | 46° | 34° |
The curve peaks near 74°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Joliet hits the closing window
Data: NOAA 1991–2020 climate normals via Joliet Brandon Rd Dam (2.6 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.