Pool swim season in Tempe, AZ
Tempe, AZ: how long the pool season really is
An unheated pool in Tempe 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).
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
What each heater buys you in Tempe
| 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 | 11 | Jan to Nov | $550 | $1,100 |
| Gas heater + cover | 11 | Jan to Nov | $1,218 | $1,643 |
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 Tempe
Heat pump + cover: 11 of 11 possible months for about $1,100 a year all-in, which works out near $220 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: Tempe Asu, 2.6 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Tempe 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° | 55° | 3.4 | 54° | 60° | $202 | $423 |
| Feb | 74° | 57° | 4.3 | 57° | 63° | $166 | $361 |
| Mar | 80° | 63° | 5.8 | 63° | 69° | $100 | $236 |
| Apr | 87° | 69° | 7.3 | 70° | 76° | $32 | $81 |
| May | 95° | 77° | 8.2 | 78° | 84° | – | – |
| Jun | 104° | 85° | 8.5 | 87° | 93° | – | – |
| Jul | 106° | 91° | 7.4 | 93° | 99° | – | – |
| Aug | 105° | 90° | 6.9 | 94° | 100° | – | – |
| Sep | 101° | 85° | 6.1 | 91° | 97° | – | – |
| Oct | 91° | 74° | 5.0 | 81° | 87° | – | – |
| Nov | 79° | 62° | 3.8 | 69° | 75° | $50 | $117 |
| Dec | 69° | 54° | 3.0 | 58° | 64° | – | – |
Heating costs most in Jan (about $202 with a heat pump, $423 with gas). Sunshine peaks in Jun at 8.5 kWh/m²/day (NASA satellite data, 41.9 km grid cell). Highlighted months are swimmable with no heater.
How Tempe compares with nearby cities
Tempe ranks 22 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 |
|---|---|---|---|---|
| Chandler, AZ | 9 mi | 6 | 11 | $550 |
| Paradise Valley, AZ | 11 mi | 6 | 9 | $157 |
| Gilbert, AZ | 12 mi | 6 | 9 | $206 |
| Mesa, AZ | 12 mi | 6 | 10 | $361 |
| Phoenix, AZ | 16 mi | 6 | 9 | $174 |
| Glendale, AZ | 18 mi | 6 | 9 | $194 |