Pool season · Maryland
Germantown Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
Germantown'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.
Each dot on the bar is one week of Germantown'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 19–May 10), solid teal is swim season, and hollow amber is the closing window ending October 11. The black marker is today — its position against the colors is the entire executive summary.
The Germantown pool calendar
Opening — target April 26
Target April 26; the practical window runs April 19–May 10, and the 7-day mean crosses the 61°F threshold around May 10. Cold-water starts are the cheap ones.
Closing — deadline October 11
The window opens October 1 once water leaves the algae zone; the model deadline is October 11, a week ahead of the October 29 freeze normal.
Estimated water temperature by month
This is Germantown'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 33° | 32° | 38° | 48° | 59° | 67° | 74° | 75° | 71° | 61° | 50° | 40° |
The curve peaks near 75°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Germantown hits the closing window
Data: NOAA 1991–2020 climate normals via Damascus 3 SSW (6.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.