Pool swim season in Morro Bay, CA
When can you swim in an outdoor pool in Morro Bay, CA?
An unheated pool in Morro Bay never reaches 78°F in a normal year. It peaks around 67°F in Aug. The air allows up to 2 swimmable months with a heater (Sep to Oct).
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Heater options for a Morro Bay pool, side by side
| 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 | Sep to Oct | $0 | $283 |
| Heat pump + cover | 2 | Sep to Oct | $311 | $861 |
| Gas heater + cover | 2 | Sep to Oct | $413 | $838 |
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 Morro Bay
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: Morro Bay Fire Dept, 1.3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Morro 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 | 65° | 56° | 2.9 | 56° | 62° | – | – |
| Feb | 65° | 57° | 3.8 | 57° | 63° | – | – |
| Mar | 66° | 57° | 5.2 | 59° | 65° | – | – |
| Apr | 67° | 58° | 6.6 | 61° | 67° | – | – |
| May | 67° | 59° | 7.7 | 64° | 70° | – | – |
| Jun | 66° | 60° | 8.3 | 65° | 71° | – | – |
| Jul | 67° | 62° | 8.0 | 66° | 72° | – | – |
| Aug | 70° | 63° | 7.3 | 67° | 73° | – | – |
| Sep | 72° | 64° | 6.2 | 67° | 73° | $142 | $189 |
| Oct | 73° | 64° | 4.6 | 65° | 71° | $169 | $224 |
| Nov | 69° | 60° | 3.3 | 62° | 68° | – | – |
| Dec | 65° | 55° | 2.6 | 57° | 63° | – | – |
Heating costs most in Oct (about $169 with a heat pump, $224 with gas). Sunshine peaks in Jun at 8.3 kWh/m²/day (NASA satellite data, 36.5 km grid cell). Highlighted months are swimmable with no heater.
How Morro Bay compares with nearby cities
Morro Bay ranks 364 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 |
|---|---|---|---|---|
| Atascadero, CA | 13 mi | 0 | 7 | $683 |
| San Luis Obispo, CA | 13 mi | 0 | 7 | $981 |
| El Paso de Robles (Paso Robles), CA | 22 mi | 0 | 7 | $683 |
| Grover Beach, CA | 22 mi | 0 | 6 | $969 |
| Arroyo Grande, CA | 23 mi | 0 | 6 | $969 |
| Santa Maria, CA | 38 mi | 0 | 6 | $1,078 |