Pool swim season in Twin Falls, ID
Twin Falls, ID: how long the pool season really is
An unheated pool in Twin Falls never reaches 78°F in a normal year. It peaks around 78°F in Aug. The air allows up to 5 swimmable months with a heater (May to Sep).
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Heater options for a Twin Falls pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $0 | $0 |
| Solar cover only | 2 | Jul to Aug | $0 | $50 |
| Solar panels + cover | 4 | Jun to Sep | $0 | $283 |
| Heat pump + cover | 5 | May to Sep | $211 | $761 |
| Gas heater + cover | 5 | May to Sep | $237 | $662 |
For a 450 sq ft pool held at 80°F, at ID prices of 13.0¢/kWh electricity and $8/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Twin Falls
Solar panels + cover: 4 of 5 possible months for about $283 a year all-in, which works out near $71 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: Twin Falls-Kmvt, 1.2 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Twin Falls 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 | 40° | 31° | 1.9 | 30° | 36° | – | – |
| Feb | 46° | 35° | 2.8 | 33° | 39° | – | – |
| Mar | 56° | 44° | 4.0 | 41° | 47° | – | – |
| Apr | 63° | 49° | 5.5 | 49° | 55° | – | – |
| May | 73° | 59° | 6.7 | 58° | 64° | $134 | $146 |
| Jun | 81° | 66° | 7.6 | 67° | 73° | $51 | $61 |
| Jul | 92° | 75° | 7.6 | 75° | 81° | – | – |
| Aug | 91° | 73° | 6.6 | 78° | 84° | – | – |
| Sep | 80° | 64° | 5.3 | 71° | 77° | $26 | $30 |
| Oct | 67° | 52° | 3.6 | 58° | 64° | – | – |
| Nov | 51° | 39° | 2.2 | 45° | 51° | – | – |
| Dec | 40° | 31° | 1.5 | 34° | 40° | – | – |
Heating costs most in May (about $134 with a heat pump, $146 with gas). Sunshine peaks in Jun at 7.6 kWh/m²/day (NASA satellite data, 7.8 km grid cell). Highlighted months are swimmable with no heater.
How Twin Falls compares with nearby cities
Twin Falls ranks 11 of 26 Idaho cities for unheated swim months; Mountain Home, Boise City nearby get a longer season without a heater.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Jerome, ID | 11 mi | 0 | 4 | $89 |
| Burley, ID | 34 mi | 0 | 4 | $140 |
| Mountain Home, ID | 74 mi | 1 | 5 | $186 |
| Pocatello, ID | 104 mi | 0 | 5 | $232 |
| Chubbuck, ID | 105 mi | 0 | 4 | $119 |
| Boise City, ID | 114 mi | 1 | 5 | $167 |