Pool season · California
Vallejo Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Vallejo'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.
Vallejo, CA — 141 swim days a yearEach dot on the bar is one week of Vallejo's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (April 2–April 23), solid teal is swim season, and hollow amber is the closing window ending November 11. The black marker is today — its position against the colors is the entire executive summary.
The Vallejo pool calendar
Opening — target April 9
Open by April 9 — a two-week head start on the April 23 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline November 11
Hold the cover until November 1, then winterize by November 11, a week ahead of the December 27 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Vallejo'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 49° | 52° | 56° | 58° | 62° | 67° | 70° | 71° | 71° | 70° | 61° | 52° |
The curve peaks near 72°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Vacaville's pool season and Victorville's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Vallejo pool season FAQ
When should I open my pool in Vallejo, CA?
Open by April 9 — the model places Vallejo's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Vallejo opening guide has the 12-step sequence.
When should I close my pool in Vallejo?
Close by November 11: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Vallejo closing guide sequences the work backward from that date.
How long is the swim season in Vallejo?
Vallejo averages 141 days a year with normal highs of 80°F or better — about 8 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 Vallejo?
An unheated pool near Vallejo typically peaks around 72°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 Vallejo hits the closing window
Data: NOAA 1991–2020 climate normals via Vallejo (2.7 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.