Pool season · California
Vacaville Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
This is the one-page view of Vacaville'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.
Vacaville, CA — 158 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Vacaville's swim season; the hollow teal run before it (April 4 to April 25) is when to open; the hollow amber run after is when to close, with November 5 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Vacaville 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 5
Hold the cover until October 26, then winterize by November 5, a week ahead of the November 28 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Vacaville'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 47° | 49° | 54° | 57° | 63° | 70° | 76° | 76° | 75° | 69° | 59° | 50° |
The curve peaks near 77°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Upland's pool season and Vallejo's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Vacaville pool season FAQ
When should I open my pool in Vacaville, CA?
Target April 11. That date backs off two weeks from the day Vacaville's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Vacaville opening guide.
When should I close my pool in Vacaville?
The closing deadline is November 5 — late enough that the water has cooled out of the algae zone, early enough to beat Vacaville's first-freeze normal by about a week. See the Vacaville closing guide for the winterizing steps.
How long is the swim season in Vacaville?
Vacaville averages 158 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 Vacaville?
An unheated pool near Vacaville typically peaks around 77°F in high summer and bottoms out near 47°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 Vacaville hits the closing window
Data: NOAA 1991–2020 climate normals via Vacaville Nut Tree Airport (1.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.