Pool swim season in Monterey, CA
When can you swim in an outdoor pool in Monterey, CA?
An unheated pool in Monterey never reaches 78°F in a normal year. It peaks around 65°F in Aug. The air allows up to 2 swimmable months with a heater (Sep to Oct).
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What each heater buys you in Monterey
| 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 | 1 | Sep | $0 | $283 |
| Heat pump + cover | 2 | Sep to Oct | $404 | $954 |
| Gas heater + cover | 2 | Sep to Oct | $522 | $947 |
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 Monterey
Solar panels + cover: 1 of 2 possible months for about $283 a year all-in, which works out near $283 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, 1.6 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Monterey 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 | 60° | 52° | 2.7 | 52° | 58° | – | – |
| Feb | 61° | 53° | 3.6 | 53° | 59° | – | – |
| Mar | 63° | 54° | 4.9 | 56° | 62° | – | – |
| Apr | 63° | 55° | 6.2 | 58° | 64° | – | – |
| May | 64° | 56° | 7.3 | 60° | 66° | – | – |
| Jun | 66° | 58° | 8.0 | 62° | 68° | – | – |
| Jul | 67° | 60° | 7.6 | 64° | 70° | – | – |
| Aug | 69° | 61° | 6.9 | 65° | 71° | – | – |
| Sep | 71° | 62° | 5.8 | 65° | 71° | $186 | $242 |
| Oct | 71° | 61° | 4.4 | 63° | 69° | $218 | $280 |
| Nov | 64° | 56° | 3.1 | 59° | 65° | – | – |
| Dec | 59° | 52° | 2.4 | 53° | 59° | – | – |
Heating costs most in Oct (about $218 with a heat pump, $280 with gas). Sunshine peaks in Jun at 8.0 kWh/m²/day (NASA satellite data, 36.0 km grid cell). Highlighted months are swimmable with no heater.
How Monterey compares with nearby cities
Monterey ranks 370 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 |
|---|---|---|---|---|
| Pacific Grove, CA | 3 mi | 0 | 2 | $404 |
| Seaside, CA | 4 mi | 0 | 2 | $327 |
| Marina, CA | 8 mi | 0 | 5 | $823 |
| Salinas, CA | 15 mi | 0 | 5 | $758 |
| Watsonville, CA | 23 mi | 0 | 5 | $804 |
| Santa Cruz, CA | 27 mi | 0 | 6 | $1,030 |