Pool season · California
Fairfield Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Fairfield'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.
Fairfield, CA — 139 swim days a yearThe bar compresses Fairfield's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the April 4–April 25 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends November 9. Wherever the today marker sits, the nearest color change is your next appointment.
The Fairfield pool calendar
Opening — target April 11
Target April 11; the practical window runs April 4–April 25, and the 7-day mean crosses the 61°F threshold around April 25. Cold-water starts are the cheap ones.
Closing — deadline November 9
Hold the cover until October 30, then winterize by November 9, a week ahead of the December 14 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Fairfield'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 48° | 50° | 54° | 58° | 62° | 68° | 73° | 74° | 73° | 69° | 60° | 51° |
The curve peaks near 74°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Escondido's pool season and Folsom's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Fairfield pool season FAQ
When should I open my pool in Fairfield, CA?
Open by April 11 — the model places Fairfield's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Fairfield opening guide has the 12-step sequence.
When should I close my pool in Fairfield?
Close by November 9: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Fairfield closing guide sequences the work backward from that date.
How long is the swim season in Fairfield?
Fairfield averages 139 days a year with normal highs of 80°F or better — about 10 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 Fairfield?
An unheated pool near Fairfield typically peaks around 74°F in high summer and bottoms out near 48°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 Fairfield hits the closing window
Data: NOAA 1991–2020 climate normals via Fairfield (2.1 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.