Missouri Pool Season: Opening & Closing Dates by City

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

City Opening window Closing window Season
Kansas City May 1 – May 20 Sep 22 – Oct 7 ≈ 142 days
St. Louis Apr 28 – May 16 Sep 24 – Oct 10 ≈ 148 days
Springfield May 4 – May 24 Sep 19 – Oct 5 ≈ 136 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 Missouri's featured cities, typical openings spread from May 7 to May 14, closings from Sep 27 to Oct 2, and the unheated season runs 136–148 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.

Missouri planning pages

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