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Pool season · Michigan

Wyoming Pool Season: the Year on One Bar

Last updated: July 25, 2026 · dates · water temp

Wyoming'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.

Cool blue pool in a short-season northern climateWyoming, MI — 60 swim days a year
J F M A M J J A S O N D today (build date)

off-season opening window swim season closing window

Reading it takes ten seconds: 52 dots, one per week. Solid teal is Wyoming's swim season; the hollow teal run before it (May 4 to May 25) is when to open; the hollow amber run after is when to close, with September 29 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.

The Wyoming pool calendar

May 11open by
September 29close by
6080°F+ days
72°Fwater peak

Opening — target May 11

Target May 11; the practical window runs May 4–May 25, and the 7-day mean crosses the 61°F threshold around May 25. Cold-water starts are the cheap ones.

Full opening guide

Closing — deadline September 29

The window opens September 19 once water leaves the algae zone; the model deadline is September 29, a week ahead of the October 10 freeze normal.

Full closing guide

Where the water sits today

SEASONAL VIEW

Estimated unheated pool water temp (site model, ±5°F). The live estimate loads in your browser from Open-Meteo air temperatures; in a typical year Wyoming water runs about 24°F at its winter floor and 72°F at its summer peak.

40 45 50 55 60 65 70 75 80 85 58 open 65 algae

Estimated water temperature by month

Monthly averages of the site's water model run on Wyoming's own normals — the shape of a typical year, not a forecast. The widget above shows where the current year actually sits.

10°20°30°40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDec65° algae zone58° swimmable startopen May 11close Sep 2972°F peak24°F floor
Site-model seasonal water estimates for an unheated in-ground pool near E Grand Rapids — ±5°F, see methodology.
JanFebMarAprMayJunJulAugSepOctNovDec
26°24°30°41°52°64°70°71°66°56°44°34°

The curve peaks near 72°F — comfortable-water months here usually involve a heater or a solar cover.

Every station tells its own story: compare this curve with Westland's pool season and Ann Arbor's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Michigan season index.

Wyoming pool season FAQ

When should I open my pool in Wyoming, MI?

Target May 11. That date backs off two weeks from the day Wyoming's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Wyoming opening guide.

When should I close my pool in Wyoming?

The closing deadline is September 29 — late enough that the water has cooled out of the algae zone, early enough to beat Wyoming's first-freeze normal by about a week. See the Wyoming closing guide for the winterizing steps.

How long is the swim season in Wyoming?

Wyoming averages 60 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 Wyoming?

An unheated pool near Wyoming typically peaks around 72°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.

Data: NOAA 1991–2020 climate normals via E Grand Rapids (5.7 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.