Pool season · Iowa
Waterloo Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one Waterloo 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 Waterloo's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the April 24–May 15 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends October 3. Wherever the today marker sits, the nearest color change is your next appointment.
The Waterloo pool calendar
Opening — target May 1
Target May 1; the practical window runs April 24–May 15, and the 7-day mean crosses the 61°F threshold around May 15. Cold-water starts are the cheap ones.
Closing — deadline October 3
The window opens September 25 once water leaves the algae zone; the model deadline is October 3, a week ahead of the October 10 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Waterloo'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 21° | 21° | 31° | 44° | 56° | 68° | 74° | 74° | 69° | 58° | 44° | 31° |
The curve peaks near 74°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Waterloo hits the closing window
Data: NOAA 1991–2020 climate normals via Waterloo Municipal Airport (5.0 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.