Pool season · Michigan
Detroit Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Detroit 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.
Detroit, MI — 73 swim days a yearEach dot on the bar is one week of Detroit's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (May 1–May 22), solid teal is swim season, and hollow amber is the closing window ending October 6. The black marker is today — its position against the colors is the entire executive summary.
The Detroit pool calendar
Opening — target May 8
Open by May 8 — a two-week head start on the May 22 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 6
Hold the cover until September 26, then winterize by October 6, a week ahead of the October 25 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Detroit'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 28° | 26° | 32° | 43° | 54° | 65° | 73° | 73° | 69° | 59° | 47° | 36° |
The curve peaks near 74°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Dearborn's pool season and Farmington Hills's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Michigan season index.
Detroit pool season FAQ
When should I open my pool in Detroit, MI?
Open by May 8 — the model places Detroit's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Detroit opening guide has the 12-step sequence.
When should I close my pool in Detroit?
Close by October 6: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Detroit closing guide sequences the work backward from that date.
How long is the swim season in Detroit?
Detroit 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 Detroit?
An unheated pool near Detroit typically peaks around 74°F in high summer and bottoms out near 26°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 Detroit hits the closing window
Data: NOAA 1991–2020 climate normals via Dearborn #2 (4.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.