Pool swim season in Downey, CA
Swim season in Downey without a heater, and with one
An unheated pool in Downey never reaches 78°F in a normal year. It peaks around 77°F in Aug. The air allows up to 8 swimmable months with a heater (Apr to Nov).
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What each heater buys you in Downey
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $0 | $0 |
| Solar cover only | 4 | Jul to Oct | $0 | $50 |
| Solar panels + cover | 7 | Apr to Oct | $0 | $283 |
| Heat pump + cover | 8 | Apr to Nov | $566 | $1,116 |
| Gas heater + cover | 8 | Apr to Nov | $757 | $1,182 |
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 Downey
Solar panels + cover: 7 of 8 possible months for about $283 a year all-in, which works out near $40 for each month it adds.
Before you pay for any heater, buy a solar cover: on its own it adds 4 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: Long Beach Daugherty Airport, 8.8 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Downey 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 | 67° | 57° | 3.1 | 57° | 63° | – | – |
| Feb | 67° | 58° | 4.0 | 58° | 64° | – | – |
| Mar | 69° | 60° | 5.2 | 61° | 67° | – | – |
| Apr | 71° | 63° | 6.3 | 65° | 71° | $182 | $239 |
| May | 73° | 66° | 6.6 | 68° | 74° | $119 | $162 |
| Jun | 76° | 69° | 6.3 | 70° | 76° | $65 | $92 |
| Jul | 81° | 73° | 6.6 | 75° | 81° | – | – |
| Aug | 83° | 74° | 6.3 | 77° | 83° | – | – |
| Sep | 82° | 73° | 5.5 | 76° | 82° | – | – |
| Oct | 78° | 68° | 4.3 | 72° | 78° | $35 | $50 |
| Nov | 73° | 62° | 3.4 | 66° | 72° | $165 | $214 |
| Dec | 67° | 57° | 2.8 | 59° | 65° | – | – |
Heating costs most in Apr (about $182 with a heat pump, $239 with gas). Sunshine peaks in Jul at 6.6 kWh/m²/day (NASA satellite data, 59.5 km grid cell). Highlighted months are swimmable with no heater.
How Downey compares with nearby cities
Downey ranks 211 of 376 California cities for unheated swim months; Norwalk nearby gets a longer season without a heater.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Bell Gardens, CA | 2 mi | 0 | 8 | $487 |
| Paramount, CA | 3 mi | 0 | 8 | $566 |
| Norwalk, CA | 3 mi | 2 | 9 | $676 |
| Cudahy, CA | 3 mi | 0 | 8 | $487 |
| Bellflower, CA | 3 mi | 0 | 8 | $566 |
| South Gate, CA | 4 mi | 0 | 8 | $487 |