Pool season · Colorado
Fort Collins Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
Fort Collins'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.
Reading it takes ten seconds: 52 dots, one per week. Solid teal is Fort Collins's swim season; the hollow teal run before it (May 5 to May 26) is when to open; the hollow amber run after is when to close, with September 30 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Fort Collins pool calendar
Opening — target May 12
Target May 12; the practical window runs May 5–May 26, and the 7-day mean crosses the 61°F threshold around May 26. Cold-water starts are the cheap ones.
Closing — deadline September 30
Hold the cover until September 20, then winterize by September 30, a week ahead of the October 7 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Fort Collins'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 31° | 32° | 38° | 46° | 53° | 63° | 71° | 73° | 67° | 56° | 44° | 34° |
The curve peaks near 73°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Fort Collins hits the closing window
Data: NOAA 1991–2020 climate normals via Ft Collins (2.2 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.