Pool swim season in Daly City, CA
Swim season in Daly City without a heater, and with one
An unheated pool in Daly City never reaches 78°F in a normal year. It peaks around 62°F in Sep. The air allows up to 0 swimmable months with a heater (no month).
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What each heater buys you in Daly City
| 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 Daly City?
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: San Francisco Oceanside, 2.9 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Daly City 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° | 52° | 2.5 | 52° | 58° | – | – |
| Feb | 60° | 54° | 3.4 | 53° | 59° | – | – |
| Mar | 61° | 54° | 4.6 | 56° | 62° | – | – |
| Apr | 60° | 55° | 6.0 | 58° | 64° | – | – |
| May | 60° | 55° | 6.7 | 59° | 65° | – | – |
| Jun | 61° | 57° | 7.3 | 60° | 66° | – | – |
| Jul | 62° | 58° | 6.5 | 61° | 67° | – | – |
| Aug | 64° | 60° | 5.8 | 62° | 68° | – | – |
| Sep | 65° | 60° | 5.1 | 62° | 68° | – | – |
| Oct | 66° | 60° | 4.0 | 61° | 67° | – | – |
| Nov | 64° | 57° | 2.8 | 58° | 64° | – | – |
| Dec | 59° | 53° | 2.1 | 54° | 60° | – | – |
Sunshine peaks in Jun at 7.3 kWh/m²/day (NASA satellite data, 22.6 km grid cell). Highlighted months are swimmable with no heater.
How Daly City compares with nearby cities
Daly City ranks 373 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 |
|---|---|---|---|---|
| San Bruno, CA | 6 mi | 0 | 3 | $588 |
| South San Francisco, CA | 6 mi | 0 | 5 | $731 |
| Pacifica, CA | 7 mi | 0 | 3 | $588 |
| Millbrae, CA | 8 mi | 0 | 5 | $731 |
| Burlingame, CA | 10 mi | 0 | 5 | $731 |
| Alameda, CA | 12 mi | 0 | 5 | $765 |