Pool season · Michigan
Warren Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Warren'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.
Warren, MI — 70 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Warren's swim season; the hollow teal run before it (April 29 to May 20) is when to open; the hollow amber run after is when to close, with October 6 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Warren pool calendar
Opening — target May 6
Target May 6; the practical window runs April 29–May 20, and the 7-day mean crosses the 61°F threshold around May 20. Cold-water starts are the cheap ones.
Closing — deadline October 6
Hold the cover until September 26, then winterize by October 6, a week ahead of the October 31 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Warren'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 28° | 26° | 32° | 43° | 54° | 66° | 73° | 74° | 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 Troy's pool season and Westland's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Michigan season index.
Warren pool season FAQ
When should I open my pool in Warren, MI?
Target May 6. That date backs off two weeks from the day Warren's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Warren opening guide.
When should I close my pool in Warren?
The closing deadline is October 6 — late enough that the water has cooled out of the algae zone, early enough to beat Warren's first-freeze normal by about a week. See the Warren closing guide for the winterizing steps.
How long is the swim season in Warren?
Warren averages 70 days a year with normal highs of 80°F or better — about 4 days earlier than the Michigan median. The Michigan season index ranks all 23 covered cities by the same metric.
How warm does pool water get in Warren?
An unheated pool near Warren 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 Warren hits the closing window
Data: NOAA 1991–2020 climate normals via Detroit City Airport (5.9 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.