Pool season · Maryland
Germantown Pool Season: the Year on One Bar
Last updated: July 25, 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.
Germantown, MD — 81 swim days a yearEach 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.
Every station tells its own story: compare this curve with Frederick's pool season and Hagerstown's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Maryland season index.
Germantown pool season FAQ
When should I open my pool in Germantown, MD?
Open by April 26 — the model places Germantown's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Germantown opening guide has the 12-step sequence.
When should I close my pool in Germantown?
Close by October 11: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Germantown closing guide sequences the work backward from that date.
How long is the swim season in Germantown?
Germantown averages 81 days a year with normal highs of 80°F or better — about 6 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 Germantown?
An unheated pool near Germantown typically peaks around 75°F in high summer and bottoms out near 32°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 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.