Pool season · California
Lancaster Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
This is the one-page view of Lancaster'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.
Each dot on the bar is one week of Lancaster's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (April 4–April 25), solid teal is swim season, and hollow amber is the closing window ending October 25. The black marker is today — its position against the colors is the entire executive summary.
The Lancaster pool calendar
Opening — target April 11
Target April 11; the practical window runs April 4–April 25, and the 7-day mean crosses the 61°F threshold around April 25. Cold-water starts are the cheap ones.
Closing — deadline October 25
The window opens October 21 once water leaves the algae zone; the model deadline is October 25, a week ahead of the November 1 freeze normal.
Estimated water temperature by month
This is Lancaster'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 44° | 46° | 51° | 56° | 63° | 73° | 80° | 82° | 78° | 68° | 57° | 46° |
Warmest water typically July–September (peaking near 83°F); heaters and covers shift any month up.
Email me when Lancaster hits the closing window
Data: NOAA 1991–2020 climate normals via Lancaster Wm J Fox Field (3.9 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.