Pool swim season in Dublin, CA
When can you swim in an outdoor pool in Dublin, CA?
An unheated pool in Dublin never reaches 78°F in a normal year. It peaks around 77°F in Aug. The air allows up to 6 swimmable months with a heater (May to Oct).
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What each heater buys you in Dublin
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $0 | $0 |
| Solar cover only | 3 | Jul to Sep | $0 | $50 |
| Solar panels + cover | 6 | May to Oct | $0 | $283 |
| Heat pump + cover | 6 | May to Oct | $366 | $916 |
| Gas heater + cover | 6 | May to Oct | $487 | $912 |
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 Dublin
Solar panels + cover: 6 of 6 possible months for about $283 a year all-in, which works out near $47 for each month it adds.
Before you pay for any heater, buy a solar cover: on its own it adds 3 months here for about $50 a year (why a cover comes first). If you get quotes, ask for gas as well as a heat pump: once the purchase price is counted, gas comes out cheaper all-in here (heat pump or gas).
Weather station: Livermore Municipal Airport, 4.7 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Dublin 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 | 57° | 48° | 2.4 | 47° | 53° | – | – |
| Feb | 61° | 50° | 3.5 | 50° | 56° | – | – |
| Mar | 65° | 54° | 4.8 | 54° | 60° | – | – |
| Apr | 69° | 57° | 6.2 | 58° | 64° | – | – |
| May | 75° | 62° | 7.5 | 64° | 70° | $193 | $252 |
| Jun | 83° | 68° | 8.3 | 71° | 77° | $63 | $88 |
| Jul | 88° | 72° | 8.2 | 75° | 81° | – | – |
| Aug | 88° | 72° | 7.4 | 77° | 83° | – | – |
| Sep | 85° | 70° | 6.0 | 74° | 80° | – | – |
| Oct | 78° | 64° | 4.4 | 68° | 74° | $110 | $147 |
| Nov | 66° | 54° | 2.9 | 59° | 65° | – | – |
| Dec | 58° | 48° | 2.2 | 50° | 56° | – | – |
Heating costs most in May (about $193 with a heat pump, $252 with gas). Sunshine peaks in Jun at 8.3 kWh/m²/day (NASA satellite data, 42.4 km grid cell). Highlighted months are swimmable with no heater.
How Dublin compares with nearby cities
Dublin ranks 225 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 |
|---|---|---|---|---|
| Pleasanton, CA | 3 mi | 0 | 6 | $366 |
| San Ramon, CA | 4 mi | 0 | 5 | $245 |
| Livermore, CA | 8 mi | 0 | 7 | $625 |
| Danville, CA | 8 mi | 0 | 5 | $245 |
| Union City, CA | 10 mi | 0 | 6 | $715 |
| Hayward, CA | 13 mi | 0 | 5 | $540 |