California Pool Season: Opening & Closing Dates by City

Local dates for every featured California city — when the water warms up, when it cools off, and how long the season actually lasts.

City Opening window Closing window Season
Los Angeles Mar 26 – Jun 3 Oct 22 – Nov 21 ≈ 186 days
San Diego Apr 3 – Jun 22 Oct 16 – Nov 19 ≈ 168 days
San Francisco Heater territory — peaks in September —
Sacramento Apr 18 – May 17 Oct 8 – Oct 27 ≈ 169 days
Fresno Apr 13 – May 7 Oct 12 – Oct 28 ≈ 178 days

Windows show the stretch when each city's daily average passes through the low-to-mid 60s°F (1991–2020 NOAA records, nearest station to each city). Click a city for its month-by-month table and full season notes.

Season geography

Across California's featured cities, typical openings spread from Apr 25 to May 18, closings from Oct 18 to Nov 5, and the unheated season runs 0–186 days depending on where you are. In San Francisco, unheated outdoor swimming never quite arrives — those pages cover the heater math instead. Elevation, coastal water, and urban heat all pull real dates around, which is exactly why a state-level answer isn't enough.

For your exact town, the pool season lookup takes a ZIP code. Opening day itself is a chemistry job — the dosing calculator turns your first test reading of the year into exact amounts.

California planning pages

When to open — California When to close — California All states →