Pool season · California
El Cajon Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
El Cajon'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.
El Cajon, CA — 132 swim days a yearThe bar compresses El Cajon's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the March 9–March 30 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends November 26. Wherever the today marker sits, the nearest color change is your next appointment.
The El Cajon pool calendar
Opening — target March 16
Open by March 16 — a two-week head start on the March 30 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline November 26
The window opens November 16 once water leaves the algae zone; the model deadline is November 26, a week ahead of the December 21 freeze normal.
Estimated water temperature by month
This is El Cajon'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 55° | 56° | 58° | 61° | 64° | 68° | 73° | 76° | 76° | 71° | 65° | 57° |
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 Eastvale's pool season and El Monte's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
El Cajon pool season FAQ
When should I open my pool in El Cajon, CA?
Open by March 16 — the model places El Cajon's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The El Cajon opening guide has the 12-step sequence.
When should I close my pool in El Cajon?
Close by November 26: cool water keeps its winter chemistry, but freeze damage is the hard stop. The El Cajon closing guide sequences the work backward from that date.
How long is the swim season in El Cajon?
El Cajon averages 132 days a year with normal highs of 80°F or better — about 16 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 El Cajon?
An unheated pool near El Cajon typically peaks around 77°F in high summer and bottoms out near 55°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 El Cajon hits the closing window
Data: NOAA 1991–2020 climate normals via El Cajon (1.9 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.