Pool swim season in Portland, OR
When can you swim in an outdoor pool in Portland, OR?
An unheated pool in Portland never reaches 78°F in a normal year. It peaks around 72°F in Aug. The air allows up to 4 swimmable months with a heater (Jun to Sep).
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Heater options for a Portland pool, side by side
| 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 | 4 | Jun to Sep | $191 | $741 |
| Gas heater + cover | 4 | Jun to Sep | $416 | $841 |
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 Portland
Solar panels + cover: 4 of 4 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: Portland Kgw-Tv, 2.3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Portland 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 | 47° | 42° | 1.2 | 40° | 46° | – | – |
| Feb | 51° | 45° | 2.1 | 43° | 49° | – | – |
| Mar | 56° | 48° | 3.0 | 47° | 53° | – | – |
| Apr | 61° | 53° | 4.3 | 52° | 58° | – | – |
| May | 68° | 59° | 5.4 | 58° | 64° | – | – |
| Jun | 73° | 63° | 6.0 | 64° | 70° | $93 | $196 |
| Jul | 80° | 69° | 6.8 | 70° | 76° | $35 | $79 |
| Aug | 81° | 70° | 5.8 | 72° | 78° | $15 | $36 |
| Sep | 75° | 65° | 4.3 | 69° | 75° | $48 | $105 |
| Oct | 63° | 55° | 2.6 | 60° | 66° | – | – |
| Nov | 52° | 47° | 1.4 | 50° | 56° | – | – |
| Dec | 46° | 42° | 1.0 | 42° | 48° | – | – |
Heating costs most in Jun (about $93 with a heat pump, $196 with gas). Sunshine peaks in Jul at 6.8 kWh/m²/day (NASA satellite data, 12.4 km grid cell). Highlighted months are swimmable with no heater.
How Portland compares with nearby cities
Portland ranks 19 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 |
|---|---|---|---|---|
| Milwaukie, OR | 7 mi | 0 | 4 | $191 |
| Vancouver, WA | 7 mi | 0 | 4 | $145 |
| Lake Oswego, OR | 9 mi | 0 | 5 | $290 |
| Beaverton, OR | 9 mi | 0 | 5 | $395 |
| Happy Valley, OR | 10 mi | 0 | 5 | $290 |
| Tigard, OR | 10 mi | 0 | 5 | $395 |