Pool swim season in Imperial, CA
When can you swim in an outdoor pool in Imperial, CA?
An unheated pool in Imperial reaches 78°F in May to Oct, about 6 months a year. The air allows up to 11 swimmable months with a heater (Jan to Nov).
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Heater options for a Imperial pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 6 | May to Oct | $0 | $0 |
| Solar cover only | 7 | Apr to Oct | $0 | $50 |
| Solar panels + cover | 9 | Mar to Nov | $0 | $283 |
| Heat pump + cover | 11 | Jan to Nov | $951 | $1,501 |
| Gas heater + cover | 11 | Jan to Nov | $1,198 | $1,623 |
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 Imperial
Heat pump + cover: 11 of 11 possible months for about $1,501 a year all-in, which works out near $300 for each month it adds.
Before you pay for any heater, buy a solar cover: on its own it adds 1 month 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: Imperial County Airport, 0.4 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Imperial 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 | 71° | 56° | 3.6 | 56° | 62° | $385 | $459 |
| Feb | 74° | 59° | 4.5 | 59° | 65° | $300 | $376 |
| Mar | 80° | 65° | 6.0 | 65° | 71° | $163 | $222 |
| Apr | 86° | 71° | 7.3 | 72° | 78° | $28 | $42 |
| May | 94° | 78° | 8.1 | 80° | 86° | – | – |
| Jun | 104° | 87° | 8.4 | 88° | 94° | – | – |
| Jul | 108° | 93° | 7.7 | 95° | 101° | – | – |
| Aug | 108° | 94° | 7.2 | 98° | 104° | – | – |
| Sep | 102° | 87° | 6.3 | 94° | 100° | – | – |
| Oct | 90° | 75° | 5.1 | 83° | 89° | – | – |
| Nov | 78° | 63° | 3.9 | 70° | 76° | $75 | $99 |
| Dec | 69° | 55° | 3.2 | 59° | 65° | – | – |
Heating costs most in Jan (about $385 with a heat pump, $459 with gas). Sunshine peaks in Jun at 8.4 kWh/m²/day (NASA satellite data, 38.3 km grid cell). Highlighted months are swimmable with no heater.
How Imperial compares with nearby cities
Imperial ranks 8 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 |
|---|---|---|---|---|
| El Centro, CA | 4 mi | 6 | 11 | $836 |
| Brawley, CA | 10 mi | 6 | 12 | $1,201 |
| Calexico, CA | 12 mi | 6 | 11 | $836 |
| Somerton, AZ | 53 mi | 6 | 10 | $174 |
| San Luis, AZ | 55 mi | 6 | 10 | $174 |
| Yuma, AZ | 65 mi | 6 | 10 | $174 |