Pool swim season in Douglas, AZ
When can you swim in an outdoor pool in Douglas, AZ?
An unheated pool in Douglas reaches 78°F in Jun to Sep, about 4 months a year. The air allows up to 9 swimmable months with a heater (Mar to Nov).
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Heater options for a Douglas pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 4 | Jun to Sep | $0 | $0 |
| Solar cover only | 6 | May to Oct | $0 | $50 |
| Solar panels + cover | 7 | Apr to Oct | $0 | $283 |
| Heat pump + cover | 9 | Mar to Nov | $404 | $954 |
| Gas heater + cover | 9 | Mar to Nov | $893 | $1,318 |
For a 450 sq ft pool held at 80°F, at AZ prices of 15.4¢/kWh electricity and $19/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Douglas
Heat pump + cover: 9 of 9 possible months for about $954 a year all-in, which works out near $191 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: Douglas, 3.8 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Douglas 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° | 48° | 3.8 | 49° | 55° | – | – |
| Feb | 69° | 52° | 4.7 | 52° | 58° | – | – |
| Mar | 73° | 56° | 6.1 | 57° | 63° | $168 | $361 |
| Apr | 81° | 63° | 7.5 | 64° | 70° | $89 | $210 |
| May | 89° | 71° | 8.2 | 72° | 78° | $14 | $36 |
| Jun | 97° | 79° | 8.1 | 80° | 86° | – | – |
| Jul | 95° | 81° | 6.7 | 84° | 90° | – | – |
| Aug | 93° | 79° | 6.4 | 83° | 89° | – | – |
| Sep | 90° | 75° | 5.8 | 80° | 86° | – | – |
| Oct | 83° | 66° | 5.2 | 73° | 79° | $11 | $27 |
| Nov | 74° | 56° | 4.1 | 62° | 68° | $122 | $259 |
| Dec | 65° | 48° | 3.4 | 52° | 58° | – | – |
Heating costs most in Mar (about $168 with a heat pump, $361 with gas). Sunshine peaks in May at 8.2 kWh/m²/day (NASA satellite data, 11.9 km grid cell). Highlighted months are swimmable with no heater.
How Douglas compares with nearby cities
Douglas ranks 35 of 44 Arizona cities for unheated swim months; Tucson nearby gets a longer season without a heater.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Sierra Vista, AZ | 47 mi | 2 | 9 | $552 |
| Nogales, AZ | 82 mi | 4 | 9 | $404 |
| Sahuarita, AZ | 91 mi | 4 | 9 | $262 |
| Tucson, AZ | 94 mi | 5 | 9 | $206 |
| Safford, AZ | 100 mi | 4 | 9 | $393 |
| Oro Valley, AZ | 110 mi | 4 | 9 | $411 |