Pool season · Washington
Seattle Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
Seattle'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 Seattle's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the May 24–June 14 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends October 1. Wherever the today marker sits, the nearest color change is your next appointment.
The Seattle pool calendar
Opening — target May 31
Open by May 31 — a two-week head start on the June 14 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 1
The window opens September 21 once water leaves the algae zone; the model deadline is October 1, a week ahead of the November 23 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Seattle'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 42° | 43° | 45° | 49° | 54° | 60° | 64° | 68° | 65° | 58° | 50° | 44° |
The curve peaks near 68°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Seattle hits the closing window
Data: NOAA 1991–2020 climate normals via Seattle Sand Pt WSFO (5.6 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.