Pool swim season in Onalaska, WI
Onalaska, WI: how long the pool season really is
An unheated pool in Onalaska never reaches 78°F in a normal year. It peaks around 76°F in Jul. The air allows up to 5 swimmable months with a heater (May to Sep).
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What each heater buys you in Onalaska
| 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 | $286 | $836 |
| Gas heater + cover | 5 | May to Sep | $315 | $740 |
For a 450 sq ft pool held at 80°F, at WI prices of 19.1¢/kWh electricity and $11/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Onalaska
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: La Crosse Municipal Airport, 2.5 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Onalaska 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 | 27° | 19° | 1.8 | 21° | 27° | – | – |
| Feb | 33° | 23° | 2.9 | 21° | 27° | – | – |
| Mar | 46° | 36° | 3.8 | 30° | 36° | – | – |
| Apr | 60° | 49° | 4.6 | 44° | 50° | – | – |
| May | 72° | 61° | 5.5 | 58° | 64° | $192 | $205 |
| Jun | 82° | 71° | 6.1 | 69° | 75° | $50 | $61 |
| Jul | 85° | 75° | 6.3 | 76° | 82° | – | – |
| Aug | 83° | 73° | 5.3 | 76° | 82° | – | – |
| Sep | 76° | 65° | 4.2 | 70° | 76° | $44 | $49 |
| Oct | 62° | 52° | 2.8 | 58° | 64° | – | – |
| Nov | 46° | 38° | 1.9 | 44° | 50° | – | – |
| Dec | 33° | 25° | 1.4 | 30° | 36° | – | – |
Heating costs most in May (about $192 with a heat pump, $205 with gas). Sunshine peaks in Jul at 6.3 kWh/m²/day (NASA satellite data, 49.4 km grid cell). Highlighted months are swimmable with no heater.
How Onalaska compares with nearby cities
Onalaska ranks 1 of 98 Wisconsin cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| La Crosse, WI | 5 mi | 0 | 4 | $218 |
| Holmen, WI | 6 mi | 0 | 5 | $286 |
| Winona, MN | 26 mi | 0 | 5 | $247 |
| Rochester, MN | 64 mi | 0 | 4 | $195 |
| Reedsburg, WI | 65 mi | 0 | 4 | $200 |
| Eau Claire, WI | 66 mi | 0 | 4 | $167 |