Pool swim season in Box Elder, SD
When can you swim in an outdoor pool in Box Elder, SD?
An unheated pool in Box Elder never reaches 78°F in a normal year. It peaks around 75°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 Box Elder 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 | 4 | Jun to Sep | $160 | $710 |
| Gas heater + cover | 4 | Jun to Sep | $213 | $638 |
For a 450 sq ft pool held at 80°F, at SD prices of 14.6¢/kWh electricity and $10/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Box Elder
Solar panels + cover: 4 of 4 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: Rapid City Regional Airport, 4.7 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Box Elder 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 | 36° | 24° | 1.9 | 24° | 30° | – | – |
| Feb | 38° | 26° | 2.9 | 25° | 31° | – | – |
| Mar | 48° | 35° | 4.0 | 32° | 38° | – | – |
| Apr | 57° | 44° | 5.0 | 42° | 48° | – | – |
| May | 67° | 54° | 5.9 | 52° | 58° | – | – |
| Jun | 78° | 65° | 6.8 | 63° | 69° | $92 | $124 |
| Jul | 86° | 72° | 7.0 | 73° | 79° | $12 | $17 |
| Aug | 85° | 71° | 6.0 | 75° | 81° | – | – |
| Sep | 76° | 61° | 4.7 | 68° | 74° | $56 | $72 |
| Oct | 60° | 47° | 3.1 | 54° | 60° | – | – |
| Nov | 47° | 35° | 2.1 | 40° | 46° | – | – |
| Dec | 37° | 26° | 1.6 | 29° | 35° | – | – |
Heating costs most in Jun (about $92 with a heat pump, $124 with gas). Sunshine peaks in Jul at 7.0 kWh/m²/day (NASA satellite data, 54.6 km grid cell). Highlighted months are swimmable with no heater.
How Box Elder compares with nearby cities
Box Elder ranks 9 of 14 South Dakota cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Rapid City, SD | 7 mi | 0 | 4 | $136 |
| Spearfish, SD | 45 mi | 0 | 4 | $198 |
| Gillette, WY | 120 mi | 0 | 4 | $166 |
| Pierre, SD | 138 mi | 0 | 4 | $99 |
| Scottsbluff, NE | 158 mi | 0 | 4 | $93 |
| Casper, WY | 185 mi | 0 | 4 | $151 |