Pool swim season in Rock Island, IL
When can you swim in an outdoor pool in Rock Island, IL?
An unheated pool in Rock Island never reaches 78°F in a normal year. It peaks around 77°F in Jul. The air allows up to 5 swimmable months with a heater (May to Sep).
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Heater options for a Rock Island 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 | $232 | $782 |
| Gas heater + cover | 5 | May to Sep | $270 | $695 |
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 Rock Island
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 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: Moline Quad City International Airport, 3.5 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Rock Island 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 | 32° | 23° | 1.8 | 25° | 31° | – | – |
| Feb | 37° | 28° | 2.8 | 25° | 31° | – | – |
| Mar | 50° | 40° | 3.7 | 34° | 40° | – | – |
| Apr | 63° | 51° | 4.8 | 47° | 53° | – | – |
| May | 74° | 63° | 5.6 | 60° | 66° | $167 | $189 |
| Jun | 83° | 72° | 6.2 | 71° | 77° | $35 | $46 |
| Jul | 86° | 76° | 6.3 | 77° | 83° | – | – |
| Aug | 84° | 73° | 5.5 | 77° | 83° | – | – |
| Sep | 78° | 66° | 4.5 | 71° | 77° | $30 | $35 |
| Oct | 65° | 54° | 3.0 | 60° | 66° | – | – |
| Nov | 50° | 40° | 2.1 | 46° | 52° | – | – |
| Dec | 37° | 29° | 1.5 | 33° | 39° | – | – |
Heating costs most in May (about $167 with a heat pump, $189 with gas). Sunshine peaks in Jul at 6.3 kWh/m²/day (NASA satellite data, 7.9 km grid cell). Highlighted months are swimmable with no heater.
How Rock Island compares with nearby cities
Rock Island ranks 72 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 |
|---|---|---|---|---|
| Moline, IL | 5 mi | 0 | 5 | $232 |
| Davenport, IA | 6 mi | 0 | 5 | $198 |
| Bettendorf, IA | 9 mi | 0 | 5 | $187 |
| East Moline, IL | 11 mi | 0 | 5 | $246 |
| Muscatine, IA | 25 mi | 0 | 5 | $185 |
| Clinton, IA | 31 mi | 0 | 5 | $194 |