Pool season · California
San Marcos Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one San Marcos 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.
The bar compresses San Marcos's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the March 5–March 26 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends November 28. Wherever the today marker sits, the nearest color change is your next appointment.
The San Marcos pool calendar
Opening — target March 12
Open by March 12 — a two-week head start on the March 26 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline November 28
The window opens November 18 once water leaves the algae zone; the model deadline is November 28, a week ahead of the December 30 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on San Marcos'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 56° | 57° | 59° | 62° | 65° | 69° | 74° | 77° | 77° | 72° | 66° | 58° |
The curve peaks near 77°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when San Marcos hits the closing window
Data: NOAA 1991–2020 climate normals via Escondido #2 (5.0 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.