Pool swim season in Mount Pleasant, SC
Swim season in Mount Pleasant without a heater, and with one
An unheated pool in Mount Pleasant reaches 78°F in Jun to Sep, about 4 months a year. The air allows up to 7 swimmable months with a heater (Apr to Oct).
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What each heater buys you in Mount Pleasant
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 4 | Jun to Sep | $0 | $0 |
| Solar cover only | 5 | Jun to Oct | $0 | $50 |
| Solar panels + cover | 7 | Apr to Oct | $0 | $283 |
| Heat pump + cover | 7 | Apr to Oct | $124 | $674 |
| Gas heater + cover | 7 | Apr to Oct | $266 | $691 |
For a 450 sq ft pool held at 80°F, at SC prices of 15.9¢/kWh electricity and $17/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Mount Pleasant
Solar panels + cover: 7 of 7 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 1 month 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: Sullivans Is, 3.3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Mount Pleasant 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 | 59° | 48° | 2.8 | 49° | 55° | – | – |
| Feb | 61° | 50° | 3.4 | 49° | 55° | – | – |
| Mar | 67° | 56° | 4.6 | 55° | 61° | – | – |
| Apr | 75° | 64° | 6.0 | 63° | 69° | $102 | $215 |
| May | 82° | 73° | 6.5 | 72° | 78° | $17 | $40 |
| Jun | 88° | 79° | 6.5 | 79° | 85° | – | – |
| Jul | 91° | 82° | 6.3 | 84° | 90° | – | – |
| Aug | 90° | 81° | 5.7 | 84° | 90° | – | – |
| Sep | 86° | 77° | 4.8 | 81° | 87° | – | – |
| Oct | 78° | 68° | 4.1 | 73° | 79° | $5 | $11 |
| Nov | 69° | 58° | 3.1 | 63° | 69° | – | – |
| Dec | 62° | 51° | 2.5 | 54° | 60° | – | – |
Heating costs most in Apr (about $102 with a heat pump, $215 with gas). Sunshine peaks in May at 6.5 kWh/m²/day (NASA satellite data, 48.4 km grid cell). Highlighted months are swimmable with no heater.
How Mount Pleasant compares with nearby cities
Mount Pleasant ranks 18 of 42 South Carolina cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Charleston, SC | 6 mi | 4 | 7 | $84 |
| James Island, SC | 7 mi | 4 | 7 | $84 |
| Hanahan, SC | 12 mi | 4 | 8 | $257 |
| North Charleston, SC | 14 mi | 4 | 8 | $257 |
| Goose Creek, SC | 15 mi | 4 | 8 | $257 |
| Summerville, SC | 23 mi | 3 | 7 | $180 |