Pool swim season in San Luis Obispo, CA
Swim season in San Luis Obispo without a heater, and with one
An unheated pool in San Luis Obispo never reaches 78°F in a normal year. It peaks around 71°F in Aug. The air allows up to 7 swimmable months with a heater (May to Nov).
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Heater options for a San Luis Obispo 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 | 6 | May to Oct | $0 | $283 |
| Heat pump + cover | 7 | May to Nov | $981 | $1,531 |
| Gas heater + cover | 7 | May to Nov | $1,272 | $1,697 |
For a 450 sq ft pool held at 80°F, at CA prices of 32.6¢/kWh electricity and $22/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in San Luis Obispo
Solar panels + cover: 6 of 7 possible months for about $283 a year all-in, which works out near $47 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: San Luis Obispo Mcchesney Field, 2.4 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
San Luis Obispo 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 | 65° | 53° | 2.9 | 53° | 59° | – | – |
| Feb | 65° | 54° | 3.8 | 54° | 60° | – | – |
| Mar | 67° | 56° | 5.2 | 57° | 63° | – | – |
| Apr | 69° | 57° | 6.6 | 60° | 66° | – | – |
| May | 72° | 60° | 7.7 | 63° | 69° | $216 | $273 |
| Jun | 75° | 63° | 8.3 | 67° | 73° | $138 | $182 |
| Jul | 78° | 66° | 8.0 | 70° | 76° | $81 | $112 |
| Aug | 79° | 67° | 7.3 | 71° | 77° | $57 | $79 |
| Sep | 80° | 66° | 6.2 | 70° | 76° | $76 | $105 |
| Oct | 77° | 64° | 4.6 | 67° | 73° | $143 | $190 |
| Nov | 71° | 58° | 3.3 | 61° | 67° | $270 | $331 |
| Dec | 65° | 53° | 2.6 | 55° | 61° | – | – |
Heating costs most in Nov (about $270 with a heat pump, $331 with gas). Sunshine peaks in Jun at 8.3 kWh/m²/day (NASA satellite data, 30.1 km grid cell). Highlighted months are swimmable with no heater.
How San Luis Obispo compares with nearby cities
San Luis Obispo ranks 320 of 376 California cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Grover Beach, CA | 10 mi | 0 | 6 | $969 |
| Arroyo Grande, CA | 11 mi | 0 | 6 | $969 |
| Morro Bay, CA | 13 mi | 0 | 2 | $311 |
| Atascadero, CA | 15 mi | 0 | 7 | $683 |
| El Paso de Robles (Paso Robles), CA | 25 mi | 0 | 7 | $683 |
| Santa Maria, CA | 26 mi | 0 | 6 | $1,078 |