Pool season · Pennsylvania
Harrisburg Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Harrisburg'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.
Harrisburg, PA — 81 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Harrisburg's swim season; the hollow teal run before it (April 25 to May 16) is when to open; the hollow amber run after is when to close, with October 5 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Harrisburg pool calendar
Opening — target May 2
Open by May 2 — a two-week head start on the May 16 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 5
Hold the cover until September 25, then winterize by October 5, a week ahead of the October 23 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Harrisburg's own normals — the shape of a typical year, not a forecast. The widget above shows where the current year actually sits.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 31° | 29° | 35° | 45° | 57° | 66° | 74° | 74° | 69° | 59° | 47° | 38° |
The curve peaks near 75°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Erie's pool season and Lancaster's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Pennsylvania season index.
Harrisburg pool season FAQ
When should I open my pool in Harrisburg, PA?
Open by May 2 — the model places Harrisburg's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Harrisburg opening guide has the 12-step sequence.
When should I close my pool in Harrisburg?
Close by October 5: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Harrisburg closing guide sequences the work backward from that date.
How long is the swim season in Harrisburg?
Harrisburg averages 81 days a year with normal highs of 80°F or better — right on the statewide median. The Pennsylvania season index ranks all 12 covered cities by the same metric.
How warm does pool water get in Harrisburg?
An unheated pool near Harrisburg typically peaks around 75°F in high summer and bottoms out near 29°F in winter, never quite reaching the 78°F comfort line without a heater or solar cover. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Harrisburg hits the closing window
Data: NOAA 1991–2020 climate normals via Harrisburg 1 NE (0.9 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.