Pool opening · State guide

When to Open Your Pool in California

Last updated: July 15, 2026 · 147 cities covered

California's opening calendar spans about 178 days. The earliest model date belongs to Indio (January 25), the latest to San Francisco (July 22), and the statewide median lands on April 1.

Every date is the same model — two weeks ahead of the day the local 7-day mean temperature crosses 61°F — applied to each city's own NOAA normals station. Click through for the live water estimate, the full window, and the 12-step checklist.

Dates are typical-year model outputs, not forecasts — each city guide carries the live widget that tracks the current year against them.

How to use these dates

Each "open by" date is two weeks ahead of that city's own 61°F crossing — the day its 7-day mean temperature (highs and lows averaged, from the nearest NOAA 1991–2020 normals station) reaches the level where unheated pool water starts climbing toward the 65°F algae-growth zone. Opening inside the window means starting up in cold, algae-resistant water: a single label-dosed shock instead of a green-water recovery, and a shopping trip while California stores are still fully stocked.

Dates are typical-year guidance, not forecasts. A warm or late spring shifts the real-world moment by a week or two in either direction — every city guide carries a live water-temperature widget that tracks the current year against these normals, plus the full 12-step opening checklist sequenced to its local window. New to the process? Start with the generic how-to-open guide and the chemicals shopping list, then come back for your city's dates.