Pool season · Colorado
Grand Junction Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
This is the one-page view of Grand Junction's pool year: both model windows, the estimated water-temperature curve, and today's live position on the season bar. The detailed checklists live on the opening and closing guides; this page is the calendar you check between them.
Grand Junction, CO — 120 swim days a yearEach dot on the bar is one week of Grand Junction's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (April 19–May 10), solid teal is swim season, and hollow amber is the closing window ending October 12. The black marker is today — its position against the colors is the entire executive summary.
The Grand Junction pool calendar
Opening — target April 26
Target April 26; the practical window runs April 19–May 10, and the 7-day mean crosses the 61°F threshold around May 10. Cold-water starts are the cheap ones.
Closing — deadline October 12
The window opens October 2 once water leaves the algae zone; the model deadline is October 12, a week ahead of the October 23 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Grand Junction'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 28° | 32° | 42° | 51° | 59° | 70° | 78° | 79° | 73° | 62° | 47° | 35° |
Warmest water typically July–August (peaking near 80°F); heaters and covers shift any month up.
Every station tells its own story: compare this curve with Fort Collins's pool season and Greeley's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Colorado season index.
Grand Junction pool season FAQ
When should I open my pool in Grand Junction, CO?
Open by April 26 — the model places Grand Junction's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Grand Junction opening guide has the 12-step sequence.
When should I close my pool in Grand Junction?
Close by October 12: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Grand Junction closing guide sequences the work backward from that date.
How long is the swim season in Grand Junction?
Grand Junction averages 120 days a year with normal highs of 80°F or better — about 17 days earlier than the Colorado median. The Colorado season index ranks all 19 covered cities by the same metric.
How warm does pool water get in Grand Junction?
An unheated pool near Grand Junction typically peaks around 80°F in high summer and bottoms out near 28°F in winter, spending roughly 2 months at or above the 78°F comfort line most swimmers prefer. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Grand Junction hits the closing window
Data: NOAA 1991–2020 climate normals via Grand Junction Wfo (3.2 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.