Pool season · California
San Ramon Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
San Ramon'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.
Reading it takes ten seconds: 52 dots, one per week. Solid teal is San Ramon's swim season; the hollow teal run before it (May 8 to May 29) is when to open; the hollow amber run after is when to close, with November 1 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The San Ramon pool calendar
Opening — target May 15
Open by May 15 — a two-week head start on the May 29 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline November 1
Hold the cover until October 22, then winterize by November 1, a week ahead of the December 22 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is San Ramon'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 47° | 48° | 49° | 52° | 56° | 62° | 70° | 72° | 71° | 67° | 58° | 49° |
The curve peaks near 72°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when San Ramon hits the closing window
Data: NOAA 1991–2020 climate normals via Mt Diablo Junction (8.1 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.