Pool swim season in Lake Oswego, OR
Swim season in Lake Oswego without a heater, and with one
An unheated pool in Lake Oswego never reaches 78°F in a normal year. It peaks around 74°F in Aug. The air allows up to 5 swimmable months with a heater (May to Sep).
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What each heater buys you in Lake Oswego
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $0 | $0 |
| Solar cover only | 1 | Aug | $0 | $50 |
| Solar panels + cover | 4 | Jun to Sep | $0 | $283 |
| Heat pump + cover | 5 | May to Sep | $290 | $840 |
| Gas heater + cover | 5 | May to Sep | $612 | $1,037 |
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 Lake Oswego
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 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: Oregon City, 6.1 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Lake Oswego 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 | 48° | 43° | 1.2 | 40° | 46° | – | – |
| Feb | 53° | 45° | 2.1 | 43° | 49° | – | – |
| Mar | 58° | 49° | 3.0 | 47° | 53° | – | – |
| Apr | 64° | 53° | 4.3 | 52° | 58° | – | – |
| May | 71° | 60° | 5.4 | 59° | 65° | $144 | $291 |
| Jun | 76° | 65° | 6.0 | 65° | 71° | $79 | $171 |
| Jul | 84° | 71° | 6.8 | 71° | 77° | $22 | $51 |
| Aug | 84° | 71° | 5.8 | 74° | 80° | $4 | $10 |
| Sep | 78° | 65° | 4.3 | 69° | 75° | $41 | $89 |
| Oct | 65° | 56° | 2.6 | 60° | 66° | – | – |
| Nov | 53° | 47° | 1.4 | 50° | 56° | – | – |
| Dec | 47° | 42° | 1.0 | 42° | 48° | – | – |
Heating costs most in May (about $144 with a heat pump, $291 with gas). Sunshine peaks in Jul at 6.8 kWh/m²/day (NASA satellite data, 18.3 km grid cell). Highlighted months are swimmable with no heater.
How Lake Oswego compares with nearby cities
Lake Oswego ranks 11 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 |
|---|---|---|---|---|
| Tigard, OR | 4 mi | 0 | 5 | $395 |
| West Linn, OR | 4 mi | 0 | 5 | $290 |
| Milwaukie, OR | 4 mi | 0 | 4 | $191 |
| Tualatin, OR | 4 mi | 0 | 5 | $395 |
| Gladstone, OR | 6 mi | 0 | 5 | $290 |
| Beaverton, OR | 7 mi | 0 | 5 | $395 |