Pool season · Michigan
Dearborn Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Dearborn's whole pool calendar, condensed: when the water warms, when it cools, and where today falls between those edges. Use the opening guide and closing guide for the step-by-step work; keep this page for the dates.
Dearborn, MI — 73 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Dearborn's swim season; the hollow teal run before it (May 2 to May 23) is when to open; the hollow amber run after is when to close, with October 4 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Dearborn pool calendar
Opening — target May 9
Target May 9; the practical window runs May 2–May 23, and the 7-day mean crosses the 61°F threshold around May 23. Cold-water starts are the cheap ones.
Closing — deadline October 4
The window opens September 24 once water leaves the algae zone; the model deadline is October 4, a week ahead of the October 15 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Dearborn'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 27° | 25° | 31° | 42° | 54° | 64° | 72° | 72° | 68° | 58° | 46° | 35° |
The curve peaks near 73°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Battle Creek's pool season and Detroit's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Michigan season index.
Dearborn pool season FAQ
When should I open my pool in Dearborn, MI?
Open by May 9 — the model places Dearborn's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Dearborn opening guide has the 12-step sequence.
When should I close my pool in Dearborn?
Close by October 4: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Dearborn closing guide sequences the work backward from that date.
How long is the swim season in Dearborn?
Dearborn averages 73 days a year with normal highs of 80°F or better — right on the statewide median. The Michigan season index ranks all 23 covered cities by the same metric.
How warm does pool water get in Dearborn?
An unheated pool near Dearborn typically peaks around 73°F in high summer and bottoms out near 24°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 Dearborn hits the closing window
Data: NOAA 1991–2020 climate normals via Dearborn (1.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.