North Dakota Pool Season: Opening & Closing Dates by City

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

City Opening window Closing window Season
Fargo Jun 1 – Jun 24 Aug 18 – Sep 8 ≈ 80 days
Bismarck Jun 9 – Jul 6 Aug 13 – Sep 4 ≈ 66 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 North Dakota's featured cities, typical openings spread from Jun 10 to Jun 20, closings from Aug 25 to Aug 29, and the unheated season runs 66–80 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.

North Dakota planning pages

When to open — North Dakota When to close — North Dakota All states →