Pool season · South Carolina
Sumter Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
Sumter's whole pool calendar, condensed: when the water warms, when it cools, and where today falls between those edges. Use the opening guide and closing guide for the step-by-step work; keep this page for the dates.
Each dot on the bar is one week of Sumter's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (March 21–April 11), solid teal is swim season, and hollow amber is the closing window ending October 30. The black marker is today — its position against the colors is the entire executive summary.
The Sumter pool calendar
Opening — target March 28
Target March 28; the practical window runs March 21–April 11, and the 7-day mean crosses the 61°F threshold around April 11. Cold-water starts are the cheap ones.
Closing — deadline October 30
Hold the cover until October 20, then winterize by October 30, a week ahead of the November 7 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Sumter'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 45° | 45° | 50° | 58° | 66° | 74° | 79° | 79° | 76° | 68° | 57° | 49° |
Warmest water typically July–August (peaking near 80°F); heaters and covers shift any month up.
Email me when Sumter hits the closing window
Data: NOAA 1991–2020 climate normals via Sumter (2.1 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.