Pool season · State index
Iowa Pool Season 2026: Opening & Closing Dates by City
Last updated: July 25, 2026 · 6 cities covered
Both halves of the pool year for all 6 covered Iowa cities. The median calendar runs May 1 to October 5. Every row links to a one-page season overview with the live water-temperature model; the opening and closing hubs carry the full checklists.
Iowa: a moderate-season pool state| City | Open by | Close by | 80°F+ days |
|---|---|---|---|
| Cedar Rapids | May 4 | Oct 2 | 75 |
| Davenport | May 1 | Oct 8 | 88 |
| Des Moines | Apr 29 | Oct 8 | 91 |
| Iowa City | Apr 28 | Oct 8 | 96 |
| Sioux City | May 6 | Sep 30 | 90 |
| Waterloo | May 1 | Oct 3 | 92 |
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 Iowa 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 Iowa
The fairest way to compare Iowa 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.
Iowa pool climate at a glance
Continental extremes rule Iowa: hot, humid summers arrive fast after cold winters, so pools cram a full season between late-spring frost risk and sharp September cooldowns. In model terms that makes Iowa a moderate-season state. The spread shows up clearly on the local pages: compare Iowa City's pool season with Sioux City's and the difference is measured in weeks, not days. Neighbors in the index run on their own normals too — see Indiana and Kansas for the adjacent calendars.
Iowa pool season FAQ
When do pools open in Iowa?
Model openings in Iowa run from April 28 in Iowa City to May 6 in Sioux City, with the statewide median on May 1. 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 Iowa?
The median Iowa closing deadline is October 8, 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 Iowa city has the longest swim season?
Iowa City leads with 96 days of 80°F+ highs per year, while Cedar Rapids brings up the rear at 75 days. The chart above ranks every covered city by the same metric.