Pool swim season in Cornelius, OR
Cornelius, OR: how long the pool season really is
An unheated pool in Cornelius never reaches 78°F in a normal year. It peaks around 71°F in Aug. The air allows up to 4 swimmable months with a heater (Jun to Sep).
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Heater options for a Cornelius pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $0 | $0 |
| Solar cover only | 0 | no month | $0 | $50 |
| Solar panels + cover | 3 | Jul to Sep | $0 | $283 |
| Heat pump + cover | 4 | Jun to Sep | $261 | $811 |
| Gas heater + cover | 4 | Jun to Sep | $554 | $979 |
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 Cornelius
Solar panels + cover: 3 of 4 possible months for about $283 a year all-in, which works out near $94 for each month it adds.
A solar cover alone adds no swim months here, so if you want a longer season you need a heater (why); still use one at night to hold the heat you pay for. 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: Forest Grove, 2.5 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Cornelius 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 | 45° | 39° | 1.2 | 37° | 43° | – | – |
| Feb | 49° | 41° | 2.1 | 39° | 45° | – | – |
| Mar | 55° | 45° | 3.0 | 43° | 49° | – | – |
| Apr | 60° | 50° | 4.3 | 49° | 55° | – | – |
| May | 68° | 57° | 5.4 | 56° | 62° | – | – |
| Jun | 73° | 61° | 6.0 | 62° | 68° | $112 | $231 |
| Jul | 81° | 68° | 6.8 | 68° | 74° | $49 | $110 |
| Aug | 82° | 68° | 5.8 | 71° | 77° | $30 | $67 |
| Sep | 76° | 62° | 4.3 | 67° | 73° | $70 | $146 |
| Oct | 63° | 52° | 2.6 | 57° | 63° | – | – |
| Nov | 51° | 44° | 1.4 | 46° | 52° | – | – |
| Dec | 44° | 38° | 1.0 | 39° | 45° | – | – |
Heating costs most in Jun (about $112 with a heat pump, $231 with gas). Sunshine peaks in Jul at 6.8 kWh/m²/day (NASA satellite data, 35.1 km grid cell). Highlighted months are swimmable with no heater.
How Cornelius compares with nearby cities
Cornelius ranks 42 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 |
|---|---|---|---|---|
| Forest Grove, OR | 3 mi | 0 | 4 | $261 |
| Hillsboro, OR | 6 mi | 0 | 4 | $279 |
| Beaverton, OR | 12 mi | 0 | 5 | $395 |
| Tigard, OR | 15 mi | 0 | 5 | $395 |
| Sherwood, OR | 15 mi | 0 | 4 | $245 |
| Newberg, OR | 15 mi | 0 | 4 | $245 |