Pool season · Pennsylvania
Philadelphia Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
Philadelphia'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.
Reading it takes ten seconds: 52 dots, one per week. Solid teal is Philadelphia's swim season; the hollow teal run before it (April 8 to April 29) is when to open; the hollow amber run after is when to close, with October 22 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Philadelphia pool calendar
Opening — target April 15
Open by April 15 — a two-week head start on the April 29 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 22
The window opens October 12 once water leaves the algae zone; the model deadline is October 22, a week ahead of the November 17 freeze normal.
Estimated water temperature by month
This is Philadelphia'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 36° | 35° | 41° | 51° | 62° | 71° | 79° | 80° | 76° | 65° | 54° | 44° |
Warmest water typically July–August (peaking near 80°F); heaters and covers shift any month up.
Email me when Philadelphia hits the closing window
Data: NOAA 1991–2020 climate normals via Phila Franklin Inst (4.0 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.