Pool swim season in Phoenix, AZ
When can you swim in an outdoor pool in Phoenix, AZ?
An unheated pool in Phoenix reaches 78°F in May to Oct, about 6 months a year. The air allows up to 9 swimmable months with a heater (Mar to Nov).
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What each heater buys you in Phoenix
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 6 | May to Oct | $0 | $0 |
| Solar cover only | 6 | May to Oct | $0 | $50 |
| Solar panels + cover | 9 | Mar to Nov | $0 | $283 |
| Heat pump + cover | 9 | Mar to Nov | $174 | $724 |
| Gas heater + cover | 9 | Mar to Nov | $417 | $842 |
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 Phoenix
Solar panels + cover: 9 of 9 possible months for about $283 a year all-in, which works out near $94 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 a heat pump sized to your pool's surface area; here it beats gas all-in (heat pump or gas).
Weather station: Phoenix Deer Valley Municipal Airport, 8.3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Phoenix 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° | 55° | 3.4 | 55° | 61° | – | – |
| Feb | 68° | 57° | 4.4 | 57° | 63° | – | – |
| Mar | 75° | 63° | 5.9 | 63° | 69° | $101 | $239 |
| Apr | 83° | 70° | 7.3 | 71° | 77° | $29 | $75 |
| May | 92° | 78° | 8.2 | 79° | 85° | – | – |
| Jun | 102° | 87° | 8.5 | 88° | 94° | – | – |
| Jul | 104° | 92° | 7.5 | 94° | 100° | – | – |
| Aug | 103° | 92° | 6.9 | 96° | 102° | – | – |
| Sep | 98° | 86° | 6.2 | 92° | 98° | – | – |
| Oct | 86° | 75° | 5.0 | 82° | 88° | – | – |
| Nov | 74° | 62° | 3.8 | 69° | 75° | $44 | $103 |
| Dec | 64° | 53° | 3.1 | 58° | 64° | – | – |
Heating costs most in Mar (about $101 with a heat pump, $239 with gas). Sunshine peaks in Jun at 8.5 kWh/m²/day (NASA satellite data, 38.8 km grid cell). Highlighted months are swimmable with no heater.
How Phoenix compares with nearby cities
Phoenix ranks 11 of 44 Arizona cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Glendale, AZ | 6 mi | 6 | 9 | $194 |
| Paradise Valley, AZ | 8 mi | 6 | 9 | $157 |
| El Mirage, AZ | 14 mi | 6 | 9 | $194 |
| Scottsdale, AZ | 15 mi | 5 | 9 | $250 |
| Tempe, AZ | 16 mi | 6 | 11 | $550 |
| Peoria, AZ | 19 mi | 5 | 9 | $254 |