Pool swim season in Ontario, OR
When can you swim in an outdoor pool in Ontario, OR?
An unheated pool in Ontario 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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Heater options for a Ontario pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 1 | Aug | $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 | $218 | $768 |
| Gas heater + cover | 5 | May to Sep | $456 | $881 |
For a 450 sq ft pool held at 80°F, at OR prices of 15.5¢/kWh electricity and $17/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Ontario
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 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: Ontario Ksrv, 1.3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Ontario 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 | 36° | 29° | 1.6 | 28° | 34° | – | – |
| Feb | 44° | 35° | 2.5 | 32° | 38° | – | – |
| Mar | 56° | 44° | 3.6 | 40° | 46° | – | – |
| Apr | 63° | 51° | 5.3 | 50° | 56° | – | – |
| May | 74° | 60° | 6.5 | 59° | 65° | $145 | $294 |
| Jun | 82° | 68° | 7.3 | 69° | 75° | $47 | $107 |
| Jul | 93° | 77° | 7.8 | 77° | 83° | – | – |
| Aug | 91° | 74° | 6.6 | 79° | 85° | – | – |
| Sep | 81° | 64° | 5.0 | 71° | 77° | $26 | $55 |
| Oct | 65° | 50° | 3.2 | 57° | 63° | – | – |
| Nov | 47° | 37° | 1.8 | 43° | 49° | – | – |
| Dec | 36° | 29° | 1.2 | 32° | 38° | – | – |
Heating costs most in May (about $145 with a heat pump, $294 with gas). Sunshine peaks in Jul at 7.8 kWh/m²/day (NASA satellite data, 65.0 km grid cell). Highlighted months are swimmable with no heater.
How Ontario compares with nearby cities
Ontario ranks 1 of 57 Oregon cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Middleton, ID | 28 mi | 1 | 5 | $200 |
| Caldwell, ID | 31 mi | 1 | 5 | $200 |
| Star, ID | 33 mi | 1 | 5 | $200 |
| Eagle, ID | 36 mi | 1 | 5 | $200 |
| Nampa, ID | 37 mi | 1 | 5 | $200 |
| Meridian, ID | 41 mi | 1 | 5 | $167 |