Pool swim season in Grand Junction, CO
When can you swim in an outdoor pool in Grand Junction, CO?
An unheated pool in Grand Junction reaches 78°F in Jul to Aug, about 2 months a year. The air allows up to 5 swimmable months with a heater (May to Sep).
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What each heater buys you in Grand Junction
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 2 | Jul to Aug | $0 | $0 |
| Solar cover only | 4 | Jun to Sep | $0 | $50 |
| Solar panels + cover | 5 | May to Sep | $0 | $283 |
| Heat pump + cover | 5 | May to Sep | $115 | $665 |
| Gas heater + cover | 5 | May to Sep | $151 | $576 |
For a 450 sq ft pool held at 80°F, at CO prices of 16.8¢/kWh electricity and $11/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Grand Junction
Solar cover only: 4 of 5 possible months for about $50 a year all-in, which works out near $25 for each month it adds.
Before you pay for any heater, buy a solar cover: on its own it adds 2 months here for about $50 a year (why a cover comes first). If you get quotes, ask for gas as well as a heat pump: once the purchase price is counted, gas comes out cheaper all-in here (heat pump or gas).
Weather station: Grand Junction NWS Office, 3.1 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Grand Junction month by month: air, sun and pool water
| Month | Air high | Air avg | Sun kWh/m²/day | Water, unheated | Water, covered | Heat pump $ | Gas $ |
|---|---|---|---|---|---|---|---|
| Jan | 39° | 29° | 2.6 | 29° | 35° | – | – |
| Feb | 47° | 36° | 3.5 | 33° | 39° | – | – |
| Mar | 59° | 47° | 4.8 | 43° | 49° | – | – |
| Apr | 67° | 54° | 6.0 | 53° | 59° | – | – |
| May | 77° | 63° | 7.0 | 63° | 69° | $113 | $147 |
| Jun | 89° | 74° | 8.0 | 74° | 80° | $2 | $4 |
| Jul | 95° | 80° | 7.3 | 82° | 88° | – | – |
| Aug | 91° | 77° | 6.5 | 82° | 88° | – | – |
| Sep | 82° | 69° | 5.5 | 76° | 82° | – | – |
| Oct | 67° | 55° | 4.0 | 63° | 69° | – | – |
| Nov | 52° | 41° | 2.8 | 48° | 54° | – | – |
| Dec | 39° | 30° | 2.2 | 35° | 41° | – | – |
Heating costs most in May (about $113 with a heat pump, $147 with gas). Sunshine peaks in Jun at 8.0 kWh/m²/day (NASA satellite data, 46.1 km grid cell). Highlighted months are swimmable with no heater.
How Grand Junction compares with nearby cities
Grand Junction ranks 1 of 53 Colorado cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Fruita, CO | 10 mi | 2 | 5 | $175 |
| Rifle, CO | 53 mi | 0 | 5 | $470 |
| Montrose, CO | 57 mi | 0 | 5 | $237 |
| Glenwood Springs, CO | 73 mi | 0 | 5 | $416 |
| Vernal, UT | 107 mi | 0 | 5 | $270 |
| Durango, CO | 132 mi | 0 | 5 | $478 |