Pool season · Michigan
South Lyon Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
This is the one-page view of South Lyon'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 South Lyon's swim season; the hollow teal run before it (May 8 to May 29) is when to open; the hollow amber run after is when to close, with September 28 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The South Lyon pool calendar
Opening — target May 15
Target May 15; the practical window runs May 8–May 29, and the 7-day mean crosses the 61°F threshold around May 29. Cold-water starts are the cheap ones.
Closing — deadline September 28
The window opens September 18 once water leaves the algae zone; the model deadline is September 28, a week ahead of the October 13 freeze normal.
Estimated water temperature by month
This is South Lyon's typical-year water curve: the same EWMA model as the live widget, run on the 1991–2020 normals instead of this week's weather.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 25° | 22° | 29° | 40° | 52° | 62° | 69° | 70° | 66° | 56° | 44° | 33° |
The curve peaks near 70°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when South Lyon hits the closing window
Data: NOAA 1991–2020 climate normals via Whitmore Lake 1nw (6.9 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.