Pool season · Washington
Marysville Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Marysville 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.
Marysville, WA — 0 swim days a yearEach dot on the bar is one week of Marysville'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 28–June 18), solid teal is swim season, and hollow amber is the closing window ending September 21. The black marker is today — its position against the colors is the entire executive summary.
The Marysville pool calendar
Opening — target June 4
Target June 4; the practical window runs May 28–June 18, and the 7-day mean crosses the 61°F threshold around June 18. Cold-water starts are the cheap ones.
Closing — deadline September 21
Hold the cover until September 11, then winterize by September 21, a week ahead of the November 2 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Marysville'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 41° | 42° | 44° | 48° | 54° | 59° | 63° | 66° | 63° | 56° | 48° | 42° |
The curve peaks near 66°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Kirkland's pool season and Olympia's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Washington season index.
Marysville pool season FAQ
When should I open my pool in Marysville, WA?
Target June 4. That date backs off two weeks from the day Marysville's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Marysville opening guide.
When should I close my pool in Marysville?
The closing deadline is September 21 — late enough that the water has cooled out of the algae zone, early enough to beat Marysville's first-freeze normal by about a week. See the Marysville closing guide for the winterizing steps.
How long is the swim season in Marysville?
Marysville averages 0 days a year with normal highs of 80°F or better — about 11 days later than the Washington median. The Washington season index ranks all 21 covered cities by the same metric.
How warm does pool water get in Marysville?
An unheated pool near Marysville typically peaks around 66°F in high summer and bottoms out near 40°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 Marysville hits the closing window
Data: NOAA 1991–2020 climate normals via Everett (7.5 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.