Pool season · California
Brentwood Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
This is the one-page view of Brentwood's pool year: both model windows, the estimated water-temperature curve, and today's live position on the season bar. The detailed checklists live on the opening and closing guides; this page is the calendar you check between them.
Brentwood, CA — 142 swim days a yearThe bar compresses Brentwood's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the March 27–April 17 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends November 10. Wherever the today marker sits, the nearest color change is your next appointment.
The Brentwood pool calendar
Opening — target April 3
Target April 3; the practical window runs March 27–April 17, and the 7-day mean crosses the 61°F threshold around April 17. Cold-water starts are the cheap ones.
Closing — deadline November 10
Hold the cover until October 31, then winterize by November 10, a week ahead of the December 19 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Brentwood'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 47° | 50° | 55° | 59° | 64° | 70° | 75° | 76° | 74° | 70° | 60° | 51° |
The curve peaks near 76°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Berkeley's pool season and Buena Park's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Brentwood pool season FAQ
When should I open my pool in Brentwood, CA?
The site model recommends opening by April 3 — about two weeks before Brentwood'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 Brentwood opening guide.
When should I close my pool in Brentwood?
Winterize by November 10. The model holds the deadline a week ahead of Brentwood's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Brentwood closing guide.
How long is the swim season in Brentwood?
Brentwood averages 142 days a year with normal highs of 80°F or better — right on the statewide median. The California season index ranks all 147 covered cities by the same metric.
How warm does pool water get in Brentwood?
An unheated pool near Brentwood typically peaks around 76°F in high summer and bottoms out near 47°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 Brentwood hits the closing window
Data: NOAA 1991–2020 climate normals via Antioch Pumping Plt #3 (3.8 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.