Pool season · Arizona
Flagstaff Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
Flagstaff's whole pool calendar, condensed: when the water warms, when it cools, and where today falls between those edges. Use the opening guide and closing guide for the step-by-step work; keep this page for the dates.
The bar compresses Flagstaff's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the May 26–June 16 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends September 17. Wherever the today marker sits, the nearest color change is your next appointment.
The Flagstaff pool calendar
Opening — target June 2
Target June 2; the practical window runs May 26–June 16, and the 7-day mean crosses the 61°F threshold around June 16. Cold-water starts are the cheap ones.
Closing — deadline September 17
The window opens September 7 once water leaves the algae zone; the model deadline is September 17, a week ahead of the September 28 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Flagstaff'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 30° | 31° | 35° | 41° | 48° | 57° | 65° | 66° | 62° | 53° | 42° | 33° |
The curve peaks near 67°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Flagstaff hits the closing window
Data: NOAA 1991–2020 climate normals via Flagstaff Pulliam Airport (4.0 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.