Pool season · State index
Michigan Pool Season 2026: Opening & Closing Dates by City
Last updated: July 25, 2026 · 23 cities covered
Both halves of the pool year for all 23 covered Michigan cities. The median calendar runs May 10 to October 1. Every row links to a one-page season overview with the live water-temperature model; the opening and closing hubs carry the full checklists.
Michigan: a short-season pool state| City | Open by | Close by | 80°F+ days |
|---|---|---|---|
| Ann Arbor | May 11 | Sep 29 | 74 |
| Battle Creek | May 7 | Oct 2 | 69 |
| Dearborn | May 9 | Oct 4 | 73 |
| Detroit | May 8 | Oct 6 | 73 |
| Farmington Hills | May 12 | Sep 29 | 62 |
| Flint | May 13 | Sep 28 | 47 |
| Grand Rapids | May 11 | Sep 29 | 60 |
| Holland | May 10 | Oct 1 | 59 |
| Jackson | May 9 | Sep 30 | 64 |
| Kalamazoo | May 7 | Oct 2 | 70 |
| Lansing | May 10 | Sep 30 | 65 |
| Livonia | May 12 | Sep 29 | 62 |
| Muskegon | May 11 | Oct 2 | 57 |
| Port Huron | May 12 | Oct 6 | 47 |
| Rochester Hills | May 7 | Oct 3 | 63 |
| Saginaw | May 10 | Oct 1 | 71 |
| South Lyon | May 15 | Sep 28 | 44 |
| Southfield | May 12 | Sep 29 | 62 |
| Sterling Heights | May 13 | Oct 1 | 56 |
| Troy | May 7 | Oct 3 | 63 |
| Warren | May 6 | Oct 6 | 70 |
| Westland | May 5 | Oct 5 | 72 |
| Wyoming | May 11 | Sep 29 | 60 |
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 Michigan 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 Michigan
The fairest way to compare Michigan 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.
Michigan pool climate at a glance
Surrounded by cold Great Lakes water, Michigan warms slowly in spring and cools fast in fall, keeping most outdoor pools to a short high-summer window. In model terms that makes Michigan a short-season state. The spread shows up clearly on the local pages: compare Ann Arbor's pool season with Troy's and the difference is measured in weeks, not days. Neighbors in the index run on their own normals too — see Massachusetts and Minnesota for the adjacent calendars.
Michigan pool season FAQ
When do pools open in Michigan?
Model openings in Michigan run from May 5 in Westland to May 15 in South Lyon, with the statewide median on May 10. 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 Michigan?
The median Michigan closing deadline is October 1, 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 Michigan city has the longest swim season?
Ann Arbor leads with 74 days of 80°F+ highs per year, while South Lyon brings up the rear at 44 days. The chart above ranks every covered city by the same metric.