Pool season · California
Walnut Creek Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
This is the one-page view of Walnut Creek's pool year: both model windows, the estimated water-temperature curve, and today's live position on the season bar. The detailed checklists live on the opening and closing guides; this page is the calendar you check between them.
Walnut Creek, CA — 138 swim days a yearThe bar compresses Walnut Creek's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the March 28–April 18 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends November 11. Wherever the today marker sits, the nearest color change is your next appointment.
The Walnut Creek pool calendar
Opening — target April 4
Open by April 4 — a two-week head start on the April 18 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline November 11
The window opens November 1 once water leaves the algae zone; the model deadline is November 11, a week ahead of the December 19 freeze normal.
Estimated water temperature by month
This is Walnut Creek'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 50° | 52° | 56° | 59° | 63° | 68° | 73° | 73° | 73° | 69° | 61° | 52° |
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 Vista's pool season and Watsonville's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Walnut Creek pool season FAQ
When should I open my pool in Walnut Creek, CA?
Target April 4. That date backs off two weeks from the day Walnut Creek's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Walnut Creek opening guide.
When should I close my pool in Walnut Creek?
The closing deadline is November 11 — late enough that the water has cooled out of the algae zone, early enough to beat Walnut Creek's first-freeze normal by about a week. See the Walnut Creek closing guide for the winterizing steps.
How long is the swim season in Walnut Creek?
Walnut Creek averages 138 days a year with normal highs of 80°F or better — right on the statewide median. The California season index ranks all 147 covered cities by the same metric.
How warm does pool water get in Walnut Creek?
An unheated pool near Walnut Creek typically peaks around 74°F in high summer and bottoms out near 49°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 Walnut Creek hits the closing window
Data: NOAA 1991–2020 climate normals via Concord Wwtp (5.8 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.