Pennsylvania Pool Season: Opening & Closing Dates by City

Local dates for every featured Pennsylvania city — when the water warms up, when it cools off, and how long the season actually lasts.

City Opening window Closing window Season
Philadelphia May 3 – May 22 Sep 24 – Oct 9 ≈ 142 days
Pittsburgh May 17 – Jun 8 Sep 7 – Sep 26 ≈ 114 days
Erie May 26 – Jun 14 Sep 1 – Sep 24 ≈ 103 days
Harrisburg May 18 – Jun 7 Sep 3 – Sep 22 ≈ 109 days

Windows show the stretch when each city's daily average passes through the low-to-mid 60s°F (1991–2020 NOAA records, nearest station to each city). Click a city for its month-by-month table and full season notes.

Season geography

Across Pennsylvania's featured cities, typical openings spread from May 12 to Jun 5, closings from Sep 15 to Oct 2, and the unheated season runs 103–142 days depending on where you are. Elevation, coastal water, and urban heat all pull real dates around, which is exactly why a state-level answer isn't enough.

For your exact town, the pool season lookup takes a ZIP code. Opening day itself is a chemistry job — the dosing calculator turns your first test reading of the year into exact amounts.

Pennsylvania planning pages

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