Pool season · California
Merced Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
This is the one-page view of Merced'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.
Merced, CA — 158 swim days a yearThe bar compresses Merced's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the April 3–April 24 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends November 2. Wherever the today marker sits, the nearest color change is your next appointment.
The Merced pool calendar
Opening — target April 10
Target April 10; the practical window runs April 3–April 24, and the 7-day mean crosses the 61°F threshold around April 24. Cold-water starts are the cheap ones.
Closing — deadline November 2
The window opens October 23 once water leaves the algae zone; the model deadline is November 2, a week ahead of the November 24 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Merced'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 45° | 48° | 53° | 57° | 63° | 70° | 77° | 78° | 75° | 68° | 58° | 48° |
Warmest water typically August–August (peaking near 79°F); heaters and covers shift any month up.
Every station tells its own story: compare this curve with Menifee's pool season and Milpitas's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Merced pool season FAQ
When should I open my pool in Merced, CA?
Target April 10. That date backs off two weeks from the day Merced's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Merced opening guide.
When should I close my pool in Merced?
The closing deadline is November 2 — late enough that the water has cooled out of the algae zone, early enough to beat Merced's first-freeze normal by about a week. See the Merced closing guide for the winterizing steps.
How long is the swim season in Merced?
Merced averages 158 days a year with normal highs of 80°F or better — about 9 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 Merced?
An unheated pool near Merced typically peaks around 79°F in high summer and bottoms out near 45°F in winter, spending roughly 1 month at or above the 78°F comfort line most swimmers prefer. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Merced hits the closing window
Data: NOAA 1991–2020 climate normals via Merced (2.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.