Pool swim season in Carthage, MO
When can you swim in an outdoor pool in Carthage, MO?
An unheated pool in Carthage reaches 78°F in Jul to Aug, about 2 months a year. The air allows up to 6 swimmable months with a heater (May to Oct).
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What each heater buys you in Carthage
| 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 | 6 | May to Oct | $142 | $692 |
| Gas heater + cover | 6 | May to Oct | $291 | $716 |
For a 450 sq ft pool held at 80°F, at MO prices of 14.3¢/kWh electricity and $15/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Carthage
Solar panels + cover: 5 of 6 possible months for about $283 a year all-in, which works out near $94 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 a heat pump sized to your pool's surface area; here it beats gas all-in (heat pump or gas).
Weather station: Carthage, 2.3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Carthage 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 | 45° | 34° | 2.4 | 36° | 42° | – | – |
| Feb | 50° | 39° | 3.0 | 37° | 43° | – | – |
| Mar | 59° | 48° | 4.0 | 45° | 51° | – | – |
| Apr | 70° | 58° | 5.1 | 55° | 61° | – | – |
| May | 78° | 67° | 5.7 | 65° | 71° | $69 | $149 |
| Jun | 86° | 76° | 6.7 | 75° | 81° | – | – |
| Jul | 91° | 80° | 6.5 | 82° | 88° | – | – |
| Aug | 91° | 79° | 5.8 | 83° | 89° | – | – |
| Sep | 83° | 71° | 4.9 | 77° | 83° | – | – |
| Oct | 72° | 60° | 3.6 | 66° | 72° | $73 | $142 |
| Nov | 59° | 48° | 2.6 | 54° | 60° | – | – |
| Dec | 48° | 39° | 2.1 | 43° | 49° | – | – |
Heating costs most in Oct (about $73 with a heat pump, $142 with gas). Sunshine peaks in Jun at 6.7 kWh/m²/day (NASA satellite data, 42.2 km grid cell). Highlighted months are swimmable with no heater.
How Carthage compares with nearby cities
Carthage ranks 4 of 80 Missouri cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Webb City, MO | 8 mi | 2 | 6 | $148 |
| Joplin, MO | 11 mi | 2 | 6 | $148 |
| Neosho, MO | 21 mi | 2 | 6 | $139 |
| Monett, MO | 27 mi | 2 | 5 | $95 |
| Pittsburg, KS | 28 mi | 2 | 6 | $167 |
| Miami, OK | 35 mi | 2 | 7 | $295 |