Pool season · California
Pomona Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Pomona 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.
Pomona, CA — 144 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Pomona's swim season; the hollow teal run before it (March 7 to March 28) is when to open; the hollow amber run after is when to close, with November 23 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Pomona pool calendar
Opening — target March 14
Open by March 14 — a two-week head start on the March 28 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline November 23
The window opens November 13 once water leaves the algae zone; the model deadline is November 23, a week ahead of the December 28 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Pomona'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 55° | 56° | 58° | 61° | 65° | 68° | 74° | 77° | 77° | 71° | 64° | 56° |
The curve peaks near 78°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Pleasanton's pool season and Porterville's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Pomona pool season FAQ
When should I open my pool in Pomona, CA?
The site model recommends opening by March 14 — about two weeks before Pomona's 7-day mean temperature crosses 61°F, while the water is still too cold for algae. The step-by-step sequence is in the Pomona opening guide.
When should I close my pool in Pomona?
Winterize by November 23. The model holds the deadline a week ahead of Pomona's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Pomona closing guide.
How long is the swim season in Pomona?
Pomona averages 144 days a year with normal highs of 80°F or better — about 18 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 Pomona?
An unheated pool near Pomona typically peaks around 78°F in high summer and bottoms out near 54°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 Pomona hits the closing window
Data: NOAA 1991–2020 climate normals via Pomona/fairplex (1.6 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.