Pool swim season in Sedro-Woolley, WA
When can you swim in an outdoor pool in Sedro-Woolley, WA?
An unheated pool in Sedro-Woolley never reaches 78°F in a normal year. It peaks around 66°F in Aug. The air allows up to 2 swimmable months with a heater (Jul to Aug).
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Heater options for a Sedro-Woolley 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 | 2 | Jul to Aug | $0 | $283 |
| Heat pump + cover | 2 | Jul to Aug | $138 | $688 |
| Gas heater + cover | 2 | Jul to Aug | $333 | $758 |
For a 450 sq ft pool held at 80°F, at WA prices of 14.4¢/kWh electricity and $18/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Sedro-Woolley
Solar panels + cover: 2 of 2 possible months for about $283 a year all-in, which works out near $142 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: Sedro-Woolley, 1.1 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Sedro-Woolley 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 | 46° | 40° | 1.0 | 38° | 44° | – | – |
| Feb | 49° | 42° | 1.9 | 40° | 46° | – | – |
| Mar | 53° | 45° | 2.9 | 44° | 50° | – | – |
| Apr | 58° | 50° | 4.3 | 49° | 55° | – | – |
| May | 65° | 56° | 5.5 | 55° | 61° | – | – |
| Jun | 69° | 60° | 6.0 | 61° | 67° | – | – |
| Jul | 75° | 64° | 6.5 | 65° | 71° | $74 | $178 |
| Aug | 75° | 64° | 5.5 | 66° | 72° | $64 | $155 |
| Sep | 70° | 59° | 3.9 | 63° | 69° | – | – |
| Oct | 60° | 51° | 2.2 | 55° | 61° | – | – |
| Nov | 50° | 45° | 1.1 | 46° | 52° | – | – |
| Dec | 45° | 40° | 0.8 | 40° | 46° | – | – |
Heating costs most in Jul (about $74 with a heat pump, $178 with gas). Sunshine peaks in Jul at 6.5 kWh/m²/day (NASA satellite data, 19.8 km grid cell). Highlighted months are swimmable with no heater.
How Sedro-Woolley compares with nearby cities
Sedro-Woolley ranks 78 of 91 Washington cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Burlington, WA | 5 mi | 0 | 2 | $141 |
| Mount Vernon, WA | 7 mi | 0 | 2 | $141 |
| Anacortes, WA | 18 mi | 0 | 3 | $215 |
| Bellingham, WA | 20 mi | 0 | 2 | $129 |
| Oak Harbor, WA | 24 mi | 0 | 0 | $0 |
| Arlington, WA | 24 mi | 0 | 4 | $426 |