Pool season · Washington
Renton Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Renton 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.
Renton, WA — 0 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Renton's swim season; the hollow teal run before it (May 17 to June 7) is when to open; the hollow amber run after is when to close, with October 1 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Renton pool calendar
Opening — target May 24
Target May 24; the practical window runs May 17–June 7, and the 7-day mean crosses the 61°F threshold around June 7. Cold-water starts are the cheap ones.
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
Monthly averages of the site's water model run on Renton'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° | 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 Redmond's pool season and Seattle's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Washington season index.
Renton pool season FAQ
When should I open my pool in Renton, WA?
The site model recommends opening by May 24 — about two weeks before Renton's 7-day mean temperature crosses 61°F, while the water is still too cold for algae. The step-by-step sequence is in the Renton opening guide.
When should I close my pool in Renton?
Winterize by October 1. The model holds the deadline a week ahead of Renton's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Renton closing guide.
How long is the swim season in Renton?
Renton 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 Renton?
An unheated pool near Renton 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 Renton hits the closing window
Data: NOAA 1991–2020 climate normals via Renton Municipal Airport (1.5 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.