Pool season · Maryland
Hagerstown Pool Season: the Year on One Bar
Last updated: July 25, 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.
Hagerstown, MD — 98 swim days a yearEach 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.
Every station tells its own story: compare this curve with Germantown's pool season and Salisbury's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Maryland season index.
Hagerstown pool season FAQ
When should I open my pool in Hagerstown, MD?
The site model recommends opening by April 25 — about two weeks before Hagerstown's 7-day mean temperature crosses 61°F, while the water is still too cold for algae. The step-by-step sequence is in the Hagerstown opening guide.
When should I close my pool in Hagerstown?
Winterize by October 12. The model holds the deadline a week ahead of Hagerstown's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Hagerstown closing guide.
How long is the swim season in Hagerstown?
Hagerstown averages 98 days a year with normal highs of 80°F or better — about 5 days later than the Maryland median. The Maryland season index ranks all 9 covered cities by the same metric.
How warm does pool water get in Hagerstown?
An unheated pool near Hagerstown typically peaks around 77°F in high summer and bottoms out near 31°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 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.