Pool season · Maryland
Hagerstown Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one Hagerstown 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.
Each dot on the bar is one week of Hagerstown's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (April 18–May 9), solid teal is swim season, and hollow amber is the closing window ending October 12. The black marker is today — its position against the colors is the entire executive summary.
The Hagerstown pool calendar
Opening — target April 25
Target April 25; the practical window runs April 18–May 9, and the 7-day mean crosses the 61°F threshold around May 9. Cold-water starts are the cheap ones.
Closing — deadline October 12
Hold the cover until October 2, then winterize by October 12, a week ahead of the October 28 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Hagerstown'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 32° | 32° | 38° | 48° | 59° | 69° | 75° | 76° | 71° | 61° | 49° | 40° |
The curve peaks near 77°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Hagerstown hits the closing window
Data: NOAA 1991–2020 climate normals via Hagerstown 1 E (1.2 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.