Maryland Pool Season: Opening & Closing Dates by City

Local dates for every featured Maryland city — when the water warms up, when it cools off, and how long the season actually lasts.

City Opening window Closing window Season
Baltimore Apr 29 – May 19 Sep 27 – Oct 12 ≈ 148 days
Annapolis May 6 – May 25 Sep 23 – Oct 9 ≈ 139 days
Cumberland May 13 – Jun 3 Sep 10 – Sep 27 ≈ 120 days

Windows show the stretch when each city's daily average passes through the low-to-mid 60s°F (1991–2020 NOAA records, nearest station to each city). Click a city for its month-by-month table and full season notes.

Season geography

Across Maryland's featured cities, typical openings spread from May 9 to May 23, closings from Sep 20 to Oct 4, and the unheated season runs 120–148 days depending on where you are. Elevation, coastal water, and urban heat all pull real dates around, which is exactly why a state-level answer isn't enough.

For your exact town, the pool season lookup takes a ZIP code. Opening day itself is a chemistry job — the dosing calculator turns your first test reading of the year into exact amounts.

Maryland planning pages

When to open — Maryland When to close — Maryland All states →