Pool swim season in Seaside, CA
Seaside, CA: how long the pool season really is
An unheated pool in Seaside never reaches 78°F in a normal year. It peaks around 66°F in Aug. The air allows up to 2 swimmable months with a heater (Aug to Sep).
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What each heater buys you in Seaside
| 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 | 2 | Aug to Sep | $327 | $877 |
| Gas heater + cover | 2 | Aug to Sep | $427 | $852 |
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 Seaside
Solar panels + cover: 2 of 2 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 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: Monterey Peninsul Airport, 3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Seaside 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 | 62° | 53° | 2.7 | 52° | 58° | – | – |
| Feb | 62° | 54° | 3.6 | 54° | 60° | – | – |
| Mar | 63° | 54° | 4.9 | 56° | 62° | – | – |
| Apr | 63° | 55° | 6.2 | 58° | 64° | – | – |
| May | 65° | 58° | 7.3 | 61° | 67° | – | – |
| Jun | 68° | 60° | 8.0 | 64° | 70° | – | – |
| Jul | 69° | 62° | 7.6 | 66° | 72° | – | – |
| Aug | 70° | 63° | 6.9 | 66° | 72° | $157 | $205 |
| Sep | 71° | 62° | 5.8 | 65° | 71° | $170 | $222 |
| Oct | 70° | 60° | 4.4 | 63° | 69° | – | – |
| Nov | 65° | 56° | 3.1 | 58° | 64° | – | – |
| Dec | 62° | 52° | 2.4 | 53° | 59° | – | – |
Heating costs most in Sep (about $170 with a heat pump, $222 with gas). Sunshine peaks in Jun at 8.0 kWh/m²/day (NASA satellite data, 31.6 km grid cell). Highlighted months are swimmable with no heater.
How Seaside compares with nearby cities
Seaside ranks 365 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 |
|---|---|---|---|---|
| Monterey, CA | 4 mi | 0 | 2 | $404 |
| Marina, CA | 4 mi | 0 | 5 | $823 |
| Pacific Grove, CA | 6 mi | 0 | 2 | $404 |
| Salinas, CA | 11 mi | 0 | 5 | $758 |
| Watsonville, CA | 21 mi | 0 | 5 | $804 |
| Santa Cruz, CA | 27 mi | 0 | 6 | $1,030 |