Pool season · Iowa
Iowa City Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Iowa City pool. The season bar below draws everything the model knows — opening window, prime season, closing window — against today's date, with the working details one click away on the opening and closing pages.
Iowa City, IA — 96 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Iowa City's swim season; the hollow teal run before it (April 21 to May 12) is when to open; the hollow amber run after is when to close, with October 8 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Iowa City pool calendar
Opening — target April 28
Open by April 28 — a two-week head start on the May 12 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 8
The window opens September 28 once water leaves the algae zone; the model deadline is October 8, a week ahead of the October 18 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Iowa City's own normals — the shape of a typical year, not a forecast. The widget above shows where the current year actually sits.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 24° | 24° | 34° | 46° | 57° | 69° | 75° | 75° | 70° | 60° | 46° | 33° |
The curve peaks near 76°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Des Moines's pool season and Sioux City's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Iowa season index.
Iowa City pool season FAQ
When should I open my pool in Iowa City, IA?
Target April 28. That date backs off two weeks from the day Iowa City's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Iowa City opening guide.
When should I close my pool in Iowa City?
The closing deadline is October 8 — late enough that the water has cooled out of the algae zone, early enough to beat Iowa City's first-freeze normal by about a week. See the Iowa City closing guide for the winterizing steps.
How long is the swim season in Iowa City?
Iowa City averages 96 days a year with normal highs of 80°F or better — right on the statewide median. The Iowa season index ranks all 6 covered cities by the same metric.
How warm does pool water get in Iowa City?
An unheated pool near Iowa City typically peaks around 76°F in high summer and bottoms out near 23°F in winter, never quite reaching the 78°F comfort line without a heater or solar cover. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Iowa City hits the closing window
Data: NOAA 1991–2020 climate normals via Iowa City Municipal Airport (1.7 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.