Pool season · Missouri
St. Louis Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one St. Louis 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.
Reading it takes ten seconds: 52 dots, one per week. Solid teal is St. Louis's swim season; the hollow teal run before it (April 4 to April 25) is when to open; the hollow amber run after is when to close, with October 23 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The St. Louis 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 23
Hold the cover until October 13, then winterize by October 23, a week ahead of the November 4 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is St. Louis'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 34° | 34° | 43° | 53° | 64° | 73° | 80° | 80° | 76° | 66° | 53° | 42° |
Warmest water typically July–August (peaking near 81°F); heaters and covers shift any month up.
Email me when St. Louis hits the closing window
Data: NOAA 1991–2020 climate normals via St Louis Sci Center (1.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.