Pool swim season in San Bruno, CA
Swim season in San Bruno without a heater, and with one
An unheated pool in San Bruno never reaches 78°F in a normal year. It peaks around 65°F in Sep. The air allows up to 3 swimmable months with a heater (Aug to Oct).
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Heater options for a San Bruno 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 | Aug to Sep | $0 | $283 |
| Heat pump + cover | 3 | Aug to Oct | $588 | $1,138 |
| Gas heater + cover | 3 | Aug to Oct | $766 | $1,191 |
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 Bruno
Solar panels + cover: 2 of 3 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: Pacifica 4 SSE, 3.2 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
San Bruno 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 | 58° | 52° | 2.5 | 52° | 58° | – | – |
| Feb | 60° | 53° | 3.4 | 53° | 59° | – | – |
| Mar | 61° | 54° | 4.6 | 55° | 61° | – | – |
| Apr | 64° | 56° | 6.0 | 58° | 64° | – | – |
| May | 67° | 58° | 6.7 | 61° | 67° | – | – |
| Jun | 69° | 60° | 7.3 | 63° | 69° | – | – |
| Jul | 69° | 61° | 6.5 | 64° | 70° | – | – |
| Aug | 71° | 62° | 5.8 | 64° | 70° | $189 | $247 |
| Sep | 72° | 63° | 5.1 | 65° | 71° | $181 | $238 |
| Oct | 70° | 61° | 4.0 | 63° | 69° | $218 | $281 |
| Nov | 64° | 57° | 2.8 | 59° | 65° | – | – |
| Dec | 59° | 53° | 2.1 | 54° | 60° | – | – |
Heating costs most in Oct (about $218 with a heat pump, $281 with gas). Sunshine peaks in Jun at 7.3 kWh/m²/day (NASA satellite data, 15.2 km grid cell). Highlighted months are swimmable with no heater.
How San Bruno compares with nearby cities
San Bruno ranks 368 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 |
|---|---|---|---|---|
| Millbrae, CA | 2 mi | 0 | 5 | $731 |
| Pacifica, CA | 3 mi | 0 | 3 | $588 |
| South San Francisco, CA | 4 mi | 0 | 5 | $731 |
| Burlingame, CA | 4 mi | 0 | 5 | $731 |
| Daly City, CA | 6 mi | 0 | 0 | $0 |
| Hillsborough, CA | 6 mi | 0 | 5 | $731 |