Pool season · Iowa
Sioux City Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
This is the one-page view of Sioux City's pool year: both model windows, the estimated water-temperature curve, and today's live position on the season bar. The detailed checklists live on the opening and closing guides; this page is the calendar you check between them.
Reading it takes ten seconds: 52 dots, one per week. Solid teal is Sioux City's swim season; the hollow teal run before it (April 29 to May 20) is when to open; the hollow amber run after is when to close, with September 30 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Sioux City pool calendar
Opening — target May 6
Open by May 6 — a two-week head start on the May 20 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline September 30
Hold the cover until September 24, then winterize by September 30, a week ahead of the October 7 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Sioux 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 20° | 21° | 30° | 43° | 54° | 66° | 73° | 74° | 68° | 58° | 42° | 29° |
The curve peaks near 75°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Sioux City hits the closing window
Data: NOAA 1991–2020 climate normals via Sioux City Ang (6.9 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.