Pool season · California
Napa Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Napa 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.
Napa, CA — 131 swim days a yearThe bar compresses Napa's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the April 11–May 2 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends November 5. Wherever the today marker sits, the nearest color change is your next appointment.
The Napa pool calendar
Opening — target April 18
Open by April 18 — a two-week head start on the May 2 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline November 5
Hold the cover until October 26, then winterize by November 5, a week ahead of the December 4 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Napa'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 49° | 51° | 54° | 57° | 61° | 66° | 69° | 69° | 70° | 67° | 59° | 51° |
The curve peaks near 70°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Murrieta's pool season and Newport Beach's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Napa pool season FAQ
When should I open my pool in Napa, CA?
Target April 18. That date backs off two weeks from the day Napa's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Napa opening guide.
When should I close my pool in Napa?
The closing deadline is November 5 — late enough that the water has cooled out of the algae zone, early enough to beat Napa's first-freeze normal by about a week. See the Napa closing guide for the winterizing steps.
How long is the swim season in Napa?
Napa averages 131 days a year with normal highs of 80°F or better — about 17 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 Napa?
An unheated pool near Napa typically peaks around 70°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 Napa hits the closing window
Data: NOAA 1991–2020 climate normals via Napa State Hospital (2.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.