Pool season · California
Simi Valley Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
This is the one-page view of Simi Valley'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.
Simi Valley, CA — 188 swim days a yearThe bar compresses Simi Valley's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the March 5–March 26 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 Simi Valley pool calendar
Opening — target March 12
Target March 12; the practical window runs March 5–March 26, and the 7-day mean crosses the 61°F threshold around March 26. Cold-water starts are the cheap ones.
Closing — deadline November 26
Hold the cover until November 16, then winterize by November 26, a week ahead of the December 15 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Simi Valley'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° | 56° | 58° | 62° | 65° | 70° | 76° | 79° | 78° | 73° | 65° | 57° |
Warmest water typically August–September (peaking near 79°F); heaters and covers shift any month up.
Every station tells its own story: compare this curve with Seaside's pool season and South Gate's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Simi Valley pool season FAQ
When should I open my pool in Simi Valley, CA?
Open by March 12 — the model places Simi Valley's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Simi Valley opening guide has the 12-step sequence.
When should I close my pool in Simi Valley?
Close by November 26: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Simi Valley closing guide sequences the work backward from that date.
How long is the swim season in Simi Valley?
Simi Valley averages 188 days a year with normal highs of 80°F or better — about 20 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 Simi Valley?
An unheated pool near Simi Valley typically peaks around 79°F in high summer and bottoms out near 56°F in winter, spending roughly 2 months 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 Simi Valley hits the closing window
Data: NOAA 1991–2020 climate normals via Woodland Hills Pierce College (11.6 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.