Pool season · Washington
Bellevue Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Bellevue'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.
Bellevue, WA — 0 swim days a yearEach dot on the bar is one week of Bellevue's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (May 17–June 7), solid teal is swim season, and hollow amber is the closing window ending October 1. The black marker is today — its position against the colors is the entire executive summary.
The Bellevue pool calendar
Opening — target May 24
Open by May 24 — a two-week head start on the June 7 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 16 freeze normal.
Estimated water temperature by month
This is Bellevue'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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 42° | 43° | 45° | 49° | 55° | 60° | 65° | 68° | 65° | 58° | 50° | 43° |
The curve peaks near 68°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Auburn's pool season and Bellingham's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Washington season index.
Bellevue pool season FAQ
When should I open my pool in Bellevue, WA?
Target May 24. That date backs off two weeks from the day Bellevue's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Bellevue opening guide.
When should I close my pool in Bellevue?
The closing deadline is October 1 — late enough that the water has cooled out of the algae zone, early enough to beat Bellevue's first-freeze normal by about a week. See the Bellevue closing guide for the winterizing steps.
How long is the swim season in Bellevue?
Bellevue averages 0 days a year with normal highs of 80°F or better — right on the statewide median. The Washington season index ranks all 21 covered cities by the same metric.
How warm does pool water get in Bellevue?
An unheated pool near Bellevue typically peaks around 68°F in high summer and bottoms out near 42°F in winter, never quite reaching the 78°F comfort line without a heater or solar cover. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Bellevue hits the closing window
Data: NOAA 1991–2020 climate normals via Renton Municipal Airport (7.6 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.