Pool swim season in Kalispell, MT
Kalispell, MT: how long the pool season really is
An unheated pool in Kalispell never reaches 78°F in a normal year. It peaks around 67°F in Aug. The air allows up to 4 swimmable months with a heater (Jun to Sep).
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Heater options for a Kalispell pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $0 | $0 |
| Solar cover only | 0 | no month | $0 | $50 |
| Solar panels + cover | 2 | Jul to Aug | $0 | $283 |
| Heat pump + cover | 4 | Jun to Sep | $410 | $960 |
| Gas heater + cover | 4 | Jun to Sep | $478 | $903 |
For a 450 sq ft pool held at 80°F, at MT prices of 14.1¢/kWh electricity and $9/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Kalispell
Gas heater + cover: 4 of 4 possible months for about $903 a year all-in, which works out near $226 for each month it adds.
A solar cover alone adds no swim months here, so if you want a longer season you need a heater (why); still use one at night to hold the heat you pay for. 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: Kalispell Glacier Airport, 6.7 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Kalispell 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 | 31° | 24° | 1.1 | 22° | 28° | – | – |
| Feb | 36° | 27° | 2.0 | 24° | 30° | – | – |
| Mar | 45° | 35° | 3.1 | 31° | 37° | – | – |
| Apr | 55° | 43° | 4.4 | 40° | 46° | – | – |
| May | 65° | 52° | 5.5 | 50° | 56° | – | – |
| Jun | 71° | 58° | 6.0 | 58° | 64° | $149 | $171 |
| Jul | 82° | 65° | 7.1 | 65° | 71° | $71 | $90 |
| Aug | 82° | 64° | 5.8 | 67° | 73° | $57 | $72 |
| Sep | 70° | 54° | 4.0 | 60° | 66° | $133 | $145 |
| Oct | 54° | 42° | 2.4 | 47° | 53° | – | – |
| Nov | 39° | 31° | 1.2 | 35° | 41° | – | – |
| Dec | 31° | 24° | 0.8 | 26° | 32° | – | – |
Heating costs most in Jun (about $149 with a heat pump, $171 with gas). Sunshine peaks in Jul at 7.1 kWh/m²/day (NASA satellite data, 34.0 km grid cell). Highlighted months are swimmable with no heater.
How Kalispell compares with nearby cities
Kalispell ranks 7 of 8 Montana cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Missoula, MT | 94 mi | 0 | 4 | $269 |
| Sandpoint, ID | 103 mi | 0 | 4 | $296 |
| Hayden, ID | 118 mi | 0 | 4 | $190 |
| Coeur d'Alene, ID | 120 mi | 0 | 4 | $190 |
| Rathdrum, ID | 122 mi | 0 | 4 | $190 |
| Post Falls, ID | 126 mi | 0 | 4 | $190 |