Pool season · California
Fremont Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
This is the one-page view of Fremont'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.
Fremont, CA — 0 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Fremont's swim season; the hollow teal run before it (April 21 to May 12) is when to open; the hollow amber run after is when to close, with November 2 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Fremont pool calendar
Opening — target April 28
Open by April 28 — a two-week head start on the May 12 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline November 2
Hold the cover until October 23, then winterize by November 2, a week ahead of the December 22 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Fremont'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 50° | 52° | 55° | 57° | 60° | 63° | 67° | 68° | 68° | 65° | 59° | 52° |
The curve peaks near 68°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Fontana's pool season and Fresno's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Fremont pool season FAQ
When should I open my pool in Fremont, CA?
Target April 28. That date backs off two weeks from the day Fremont's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Fremont opening guide.
When should I close my pool in Fremont?
The closing deadline is November 2 — late enough that the water has cooled out of the algae zone, early enough to beat Fremont's first-freeze normal by about a week. See the Fremont closing guide for the winterizing steps.
How long is the swim season in Fremont?
Fremont averages 0 days a year with normal highs of 80°F or better — about 27 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 Fremont?
An unheated pool near Fremont typically peaks around 68°F in high summer and bottoms out near 50°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 Fremont hits the closing window
Data: NOAA 1991–2020 climate normals via Fremont (2.1 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.