Pool season · California
San Francisco Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
San Francisco'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.
San Francisco, CA — 0 swim days a yearThe bar compresses San Francisco's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the July 15–August 5 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends November 6. Wherever the today marker sits, the nearest color change is your next appointment.
The San Francisco pool calendar
Opening — target July 22
Target July 22; the practical window runs July 15–August 5, and the 7-day mean crosses the 61°F threshold around August 5. Cold-water starts are the cheap ones.
Closing — deadline November 6
Hold the cover until October 27, then winterize by November 6, a week ahead of the December 25 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is San Francisco'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 52° | 53° | 55° | 56° | 57° | 59° | 60° | 61° | 62° | 63° | 60° | 54° |
The curve peaks near 63°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with San Diego's pool season and San Jose's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
San Francisco pool season FAQ
When should I open my pool in San Francisco, CA?
Open by July 22 — the model places San Francisco's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The San Francisco opening guide has the 12-step sequence.
When should I close my pool in San Francisco?
Close by November 6: cool water keeps its winter chemistry, but freeze damage is the hard stop. The San Francisco closing guide sequences the work backward from that date.
How long is the swim season in San Francisco?
San Francisco averages 0 days a year with normal highs of 80°F or better — about 112 days later than the California median. The California season index ranks all 147 covered cities by the same metric.
How warm does pool water get in San Francisco?
An unheated pool near San Francisco typically peaks around 63°F in high summer and bottoms out near 52°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 San Francisco hits the closing window
Data: NOAA 1991–2020 climate normals via San Francisco Dwtn (1.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.