Pool season · California
San Diego Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one San Diego 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.
San Diego, CA — 73 swim days a yearEach dot on the bar is one week of San Diego's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (March 21–April 11), solid teal is swim season, and hollow amber is the closing window ending November 27. The black marker is today — its position against the colors is the entire executive summary.
The San Diego pool calendar
Opening — target March 28
Target March 28; the practical window runs March 21–April 11, and the 7-day mean crosses the 61°F threshold around April 11. Cold-water starts are the cheap ones.
Closing — deadline November 27
Hold the cover until November 17, then winterize by November 27, a week ahead of the December 21 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is San Diego'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 56° | 57° | 58° | 60° | 63° | 66° | 70° | 73° | 74° | 70° | 65° | 58° |
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 San Buenaventura's pool season and San Francisco's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
San Diego pool season FAQ
When should I open my pool in San Diego, CA?
Open by March 28 — the model places San Diego's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The San Diego opening guide has the 12-step sequence.
When should I close my pool in San Diego?
Close by November 27: cool water keeps its winter chemistry, but freeze damage is the hard stop. The San Diego closing guide sequences the work backward from that date.
How long is the swim season in San Diego?
San Diego averages 73 days a year with normal highs of 80°F or better — about 4 days earlier than the California median. The California season index ranks all 147 covered cities by the same metric.
How warm does pool water get in San Diego?
An unheated pool near San Diego typically peaks around 74°F in high summer and bottoms out near 56°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 San Diego hits the closing window
Data: NOAA 1991–2020 climate normals via San Diego Montgomery Field (1.5 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.