Pool season · Colorado
Denver Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one Denver 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.
Each dot on the bar is one week of Denver'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 4–May 25), solid teal is swim season, and hollow amber is the closing window ending October 1. The black marker is today — its position against the colors is the entire executive summary.
The Denver pool calendar
Opening — target May 11
Open by May 11 — a two-week head start on the May 25 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 1
The window opens September 23 once water leaves the algae zone; the model deadline is October 1, a week ahead of the October 8 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Denver'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 32° | 32° | 38° | 46° | 53° | 64° | 73° | 74° | 69° | 57° | 45° | 35° |
The curve peaks near 75°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Denver hits the closing window
Data: NOAA 1991–2020 climate normals via Denver-stapleton (0.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.