Pool season · District of Columbia
Washington Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one Washington 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 Washington'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 6–April 27), solid teal is swim season, and hollow amber is the closing window ending October 21. The black marker is today — its position against the colors is the entire executive summary.
The Washington pool calendar
Opening — target April 13
Open by April 13 — a two-week head start on the April 27 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 21
The window opens October 11 once water leaves the algae zone; the model deadline is October 21, a week ahead of the November 8 freeze normal.
Estimated water temperature by month
This is Washington'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 38° | 37° | 42° | 52° | 63° | 72° | 79° | 80° | 76° | 65° | 54° | 44° |
Warmest water typically July–August (peaking near 80°F); heaters and covers shift any month up.
Email me when Washington hits the closing window
Data: NOAA 1991–2020 climate normals via National Arboretum Dc (2.5 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.