Pool swim season in London, OH
Swim season in London without a heater, and with one
An unheated pool in London never reaches 78°F in a normal year. It peaks around 74°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 London 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 | $302 | $852 |
| Gas heater + cover | 5 | May to Sep | $434 | $859 |
For a 450 sq ft pool held at 80°F, at OH prices of 18.8¢/kWh electricity and $14/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in London
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 a heat pump sized to your pool's surface area; here it beats gas all-in (heat pump or gas).
Weather station: London Fish Hatchery, 3.8 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
London 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 | 33° | 26° | 1.8 | 27° | 33° | – | – |
| Feb | 37° | 29° | 2.6 | 27° | 33° | – | – |
| Mar | 48° | 38° | 3.6 | 34° | 40° | – | – |
| Apr | 61° | 50° | 4.9 | 46° | 52° | – | – |
| May | 71° | 61° | 5.6 | 58° | 64° | $188 | $261 |
| Jun | 79° | 70° | 6.2 | 68° | 74° | $59 | $93 |
| Jul | 82° | 72° | 6.0 | 74° | 80° | – | – |
| Aug | 81° | 71° | 5.5 | 74° | 80° | – | – |
| Sep | 76° | 64° | 4.6 | 69° | 75° | $55 | $80 |
| Oct | 64° | 53° | 3.2 | 59° | 65° | – | – |
| Nov | 50° | 41° | 2.2 | 46° | 52° | – | – |
| Dec | 39° | 31° | 1.5 | 35° | 41° | – | – |
Heating costs most in May (about $188 with a heat pump, $261 with gas). Sunshine peaks in Jun at 6.2 kWh/m²/day (NASA satellite data, 44.0 km grid cell). Highlighted months are swimmable with no heater.
How London compares with nearby cities
London ranks 147 of 176 Ohio cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Hilliard, OH | 18 mi | 0 | 5 | $240 |
| Springfield, OH | 19 mi | 0 | 5 | $281 |
| Grove City, OH | 20 mi | 0 | 5 | $207 |
| Upper Arlington, OH | 22 mi | 0 | 5 | $220 |
| Dublin, OH | 22 mi | 0 | 5 | $240 |
| Urbana, OH | 22 mi | 0 | 5 | $281 |