Pool swim season in Walla Walla, WA
Walla Walla, WA: how long the pool season really is
An unheated pool in Walla Walla 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 Walla Walla pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 1 | Aug | $0 | $0 |
| Solar cover only | 3 | Jul to Sep | $0 | $50 |
| Solar panels + cover | 4 | Jun to Sep | $0 | $283 |
| Heat pump + cover | 5 | May to Sep | $187 | $737 |
| Gas heater + cover | 5 | May to Sep | $443 | $868 |
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 Walla Walla
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 2 months 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: Walla Walla Regional Airport, 3.1 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Walla Walla 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 | 42° | 36° | 1.2 | 34° | 40° | – | – |
| Feb | 47° | 40° | 2.3 | 37° | 43° | – | – |
| Mar | 56° | 47° | 3.6 | 44° | 50° | – | – |
| Apr | 63° | 53° | 5.4 | 52° | 58° | – | – |
| May | 71° | 60° | 6.5 | 60° | 66° | $125 | $287 |
| Jun | 79° | 67° | 7.2 | 68° | 74° | $49 | $124 |
| Jul | 90° | 76° | 7.7 | 76° | 82° | – | – |
| Aug | 89° | 75° | 6.4 | 79° | 85° | – | – |
| Sep | 79° | 66° | 4.7 | 72° | 78° | $13 | $32 |
| Oct | 63° | 54° | 3.0 | 60° | 66° | – | – |
| Nov | 49° | 42° | 1.6 | 47° | 53° | – | – |
| Dec | 41° | 36° | 1.0 | 37° | 43° | – | – |
Heating costs most in May (about $125 with a heat pump, $287 with gas). Sunshine peaks in Jul at 7.7 kWh/m²/day (NASA satellite data, 49.8 km grid cell). Highlighted months are swimmable with no heater.
How Walla Walla compares with nearby cities
Walla Walla ranks 2 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 |
|---|---|---|---|---|
| Pendleton, OR | 36 mi | 0 | 5 | $259 |
| Pasco, WA | 40 mi | 0 | 5 | $190 |
| Kennewick, WA | 41 mi | 1 | 5 | $141 |
| Richland, WA | 48 mi | 0 | 5 | $187 |
| Hermiston, OR | 48 mi | 1 | 5 | $202 |
| La Grande, OR | 53 mi | 0 | 4 | $200 |