Pool season · Colorado
Highlands Ranch Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Highlands Ranch'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.
Highlands Ranch, CO — 89 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Highlands Ranch's swim season; the hollow teal run before it (May 9 to May 30) 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 Highlands Ranch pool calendar
Opening — target May 16
Open by May 16 — a two-week head start on the May 30 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline September 30
Hold the cover until September 20, then winterize by September 30, a week ahead of the October 8 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Highlands Ranch'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° | 37° | 44° | 51° | 62° | 71° | 72° | 67° | 56° | 44° | 34° |
The curve peaks near 73°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Greeley's pool season and Lafayette's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Colorado season index.
Highlands Ranch pool season FAQ
When should I open my pool in Highlands Ranch, CO?
The site model recommends opening by May 16 — about two weeks before Highlands Ranch's 7-day mean temperature crosses 61°F, while the water is still too cold for algae. The step-by-step sequence is in the Highlands Ranch opening guide.
When should I close my pool in Highlands Ranch?
Winterize by September 30. The model holds the deadline a week ahead of Highlands Ranch's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Highlands Ranch closing guide.
How long is the swim season in Highlands Ranch?
Highlands Ranch averages 89 days a year with normal highs of 80°F or better — right on the statewide median. The Colorado season index ranks all 19 covered cities by the same metric.
How warm does pool water get in Highlands Ranch?
An unheated pool near Highlands Ranch typically peaks around 73°F in high summer and bottoms out near 31°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 Highlands Ranch hits the closing window
Data: NOAA 1991–2020 climate normals via Denver Centennial Airport (6.8 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.