Pool swim season in Justice, IL
Swim season in Justice without a heater, and with one
An unheated pool in Justice reaches 78°F in Aug, about 1 month a year. The air allows up to 5 swimmable months with a heater (May to Sep).
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What each heater buys you in Justice
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 1 | Aug | $0 | $0 |
| Solar cover only | 3 | Jul to Sep | $0 | $50 |
| Solar panels + cover | 4 | Jun to Sep | $0 | $283 |
| Heat pump + cover | 5 | May to Sep | $230 | $780 |
| Gas heater + cover | 5 | May to Sep | $267 | $692 |
For a 450 sq ft pool held at 80°F, at IL prices of 19.2¢/kWh electricity and $11/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Justice
Solar panels + cover: 4 of 5 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 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: Chicago Midway Airport 3SW, 2.8 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Justice 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° | 1.6 | 28° | 34° | – | – |
| Feb | 37° | 30° | 2.5 | 28° | 34° | – | – |
| Mar | 48° | 40° | 3.6 | 36° | 42° | – | – |
| Apr | 60° | 51° | 4.7 | 47° | 53° | – | – |
| May | 72° | 62° | 5.4 | 59° | 65° | $176 | $199 |
| Jun | 81° | 72° | 6.1 | 70° | 76° | $41 | $52 |
| Jul | 85° | 77° | 6.2 | 78° | 84° | – | – |
| Aug | 83° | 75° | 5.3 | 78° | 84° | – | – |
| Sep | 77° | 68° | 4.4 | 73° | 79° | $13 | $16 |
| Oct | 64° | 55° | 2.9 | 62° | 68° | – | – |
| Nov | 50° | 42° | 1.9 | 48° | 54° | – | – |
| Dec | 38° | 32° | 1.4 | 35° | 41° | – | – |
Heating costs most in May (about $176 with a heat pump, $199 with gas). Sunshine peaks in Jul at 6.2 kWh/m²/day (NASA satellite data, 39.1 km grid cell). Highlighted months are swimmable with no heater.
How Justice compares with nearby cities
Justice ranks 45 of 225 Illinois cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Bridgeview, IL | 1 mi | 1 | 5 | $230 |
| Hickory Hills, IL | 2 mi | 1 | 5 | $238 |
| Summit, IL | 3 mi | 0 | 5 | $242 |
| Burbank, IL | 3 mi | 1 | 5 | $230 |
| Palos Hills, IL | 4 mi | 1 | 5 | $238 |
| Lyons, IL | 4 mi | 0 | 5 | $242 |