Pool swim season in Half Moon Bay, CA
When can you swim in an outdoor pool in Half Moon Bay, CA?
An unheated pool in Half Moon Bay never reaches 78°F in a normal year. It peaks around 62°F in Aug. The air allows up to 0 swimmable months with a heater (no month).
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- F
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What each heater buys you in Half Moon Bay
| 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 | 0 | no month | $0 | $283 |
| Heat pump + cover | 0 | no month | $0 | $550 |
| Gas heater + cover | 0 | no month | $0 | $425 |
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.
Do you need a pool heater in Half Moon Bay?
No. Your pool is already warm for every month the air allows. A heater adds nothing.
No heater makes outdoor swimming practical here: the air is too cold in every month. If you want to swim at home, price an enclosure or an indoor pool instead, and see why a cover cannot fix this and where solar panels stop working.
Weather station: Half Moon Bay, 0.4 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Half Moon Bay 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 | 59° | 51° | 2.5 | 51° | 57° | – | – |
| Feb | 60° | 51° | 3.4 | 52° | 58° | – | – |
| Mar | 60° | 52° | 4.6 | 53° | 59° | – | – |
| Apr | 61° | 53° | 6.0 | 56° | 62° | – | – |
| May | 62° | 55° | 6.7 | 58° | 64° | – | – |
| Jun | 64° | 57° | 7.3 | 60° | 66° | – | – |
| Jul | 65° | 59° | 6.5 | 61° | 67° | – | – |
| Aug | 66° | 60° | 5.8 | 62° | 68° | – | – |
| Sep | 66° | 59° | 5.1 | 61° | 67° | – | – |
| Oct | 66° | 57° | 4.0 | 59° | 65° | – | – |
| Nov | 63° | 54° | 2.8 | 55° | 61° | – | – |
| Dec | 59° | 51° | 2.1 | 51° | 57° | – | – |
Sunshine peaks in Jun at 7.3 kWh/m²/day (NASA satellite data, 6.4 km grid cell). Highlighted months are swimmable with no heater.
How Half Moon Bay compares with nearby cities
Half Moon Bay ranks 372 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 |
|---|---|---|---|---|
| Hillsborough, CA | 8 mi | 0 | 5 | $731 |
| Belmont, CA | 9 mi | 0 | 6 | $660 |
| Millbrae, CA | 9 mi | 0 | 5 | $731 |
| Burlingame, CA | 9 mi | 0 | 5 | $731 |
| San Mateo, CA | 10 mi | 0 | 5 | $731 |
| San Carlos, CA | 10 mi | 0 | 6 | $660 |