Pool swim season in Coronado, CA
Coronado, CA: how long the pool season really is
An unheated pool in Coronado never reaches 78°F in a normal year. It peaks around 74°F in Aug. The air allows up to 6 swimmable months with a heater (Jun to Nov).
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What each heater buys you in Coronado
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $0 | $0 |
| Solar cover only | 2 | Aug to Sep | $0 | $50 |
| Solar panels + cover | 5 | Jun to Oct | $0 | $283 |
| Heat pump + cover | 6 | Jun to Nov | $412 | $962 |
| Gas heater + cover | 6 | Jun to Nov | $558 | $983 |
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 Coronado
Solar panels + cover: 5 of 6 possible months for about $283 a year all-in, which works out near $57 for each month it adds.
Before you pay for any heater, buy a solar cover: on its own it adds 2 months here for about $50 a year (why a cover comes first). If you get quotes, ask for a heat pump sized to your pool's surface area; here it beats gas all-in (heat pump or gas).
Weather station: N Is Nas, 4 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Coronado 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 | 66° | 58° | 3.2 | 58° | 64° | – | – |
| Feb | 66° | 58° | 4.1 | 59° | 65° | – | – |
| Mar | 67° | 60° | 5.2 | 61° | 67° | – | – |
| Apr | 68° | 62° | 6.1 | 64° | 70° | – | – |
| May | 69° | 64° | 6.1 | 66° | 72° | – | – |
| Jun | 71° | 66° | 5.9 | 68° | 74° | $109 | $150 |
| Jul | 74° | 70° | 6.1 | 71° | 77° | $51 | $73 |
| Aug | 77° | 72° | 6.1 | 74° | 80° | $5 | $7 |
| Sep | 77° | 71° | 5.4 | 74° | 80° | $7 | $10 |
| Oct | 75° | 67° | 4.3 | 70° | 76° | $65 | $91 |
| Nov | 71° | 62° | 3.4 | 65° | 71° | $175 | $227 |
| Dec | 66° | 57° | 2.9 | 60° | 66° | – | – |
Heating costs most in Nov (about $175 with a heat pump, $227 with gas). Sunshine peaks in Apr at 6.1 kWh/m²/day (NASA satellite data, 36.6 km grid cell). Highlighted months are swimmable with no heater.
How Coronado compares with nearby cities
Coronado ranks 280 of 376 California cities for unheated swim months; La Mesa nearby gets a longer season without a heater.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| National City, CA | 3 mi | 0 | 6 | $456 |
| Imperial Beach, CA | 7 mi | 0 | 5 | $389 |
| Chula Vista, CA | 8 mi | 0 | 7 | $665 |
| Lemon Grove, CA | 9 mi | 0 | 6 | $456 |
| La Mesa, CA | 11 mi | 2 | 9 | $834 |
| San Diego, CA | 12 mi | 0 | 8 | $699 |