Pool season · State index
District of Columbia Pool Season 2026: Opening & Closing Dates by City
Last updated: July 25, 2026 · 1 cities covered
Both halves of the pool year for all 1 covered District of Columbia cities. The median calendar runs April 13 to October 21. Every row links to a one-page season overview with the live water-temperature model; the opening and closing hubs carry the full checklists.
District of Columbia: a moderate-season pool state| City | Open by | Close by | 80°F+ days |
|---|---|---|---|
| Washington | Apr 13 | Oct 21 | 115 |
What the columns mean
"Open by" is the recommended spring date — two weeks before the city's 7-day mean temperature crosses 61°F, the model's proxy for water approaching the 65°F algae-growth zone. "Close by" is the fall deadline — ten days after the water leaves that zone, capped a week ahead of the local 50% first-freeze date. "80°F+ days" counts days whose normal high reaches 80°F: the length of the true warm-swim season, and the fairest single number for comparing District of Columbia cities against each other.
Every figure comes from each city's own NOAA 1991–2020 normals station (named in its guide's footer), so neighboring cities can legitimately differ by a few days. The season overview linked from each row adds the live water-temperature model and the full-year season bar; the state hubs above carry the step-by-step checklists.
Swim-season length across District of Columbia
The fairest way to compare District of Columbia cities is the number of days with 80°F+ normal highs — the practical warm-swim season. Every bar links to that city's one-page season overview with the live water model.
District of Columbia pool climate at a glance
Washington's notoriously hot, humid summers make pools essential from Memorial Day to Labor Day, and mild autumns often justify keeping water open into September. In model terms that makes District of Columbia a moderate-season state. The spread shows up clearly on the local pages: compare Washington's pool season and the difference is measured in weeks, not days. Neighbors in the index run on their own normals too — see Delaware and Florida for the adjacent calendars.
District of Columbia pool season FAQ
When do pools open in District of Columbia?
Model openings in District of Columbia run from April 13 in Washington to April 13 in Washington, with the statewide median on April 13. Each date is two weeks before that city's 7-day mean temperature crosses 61°F — early enough to start up in algae-cold water.
When should you close a pool in District of Columbia?
The median District of Columbia closing deadline is October 21, and every city's own deadline is capped a week ahead of its NOAA 50% first-freeze date. Closing late and cold beats closing early and warm — cool water holds its winter chemistry far better.
Which District of Columbia city has the longest swim season?
Washington leads with 115 days of 80°F+ highs per year. The chart above ranks every covered city by the same metric.