Pool swim season in Fresno, CA
Swim season in Fresno without a heater, and with one
An unheated pool in Fresno reaches 78°F in Jun to Sep, about 4 months a year. The air allows up to 7 swimmable months with a heater (Apr to Oct).
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Heater options for a Fresno pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 4 | Jun to Sep | $0 | $0 |
| Solar cover only | 5 | Jun to Oct | $0 | $50 |
| Solar panels + cover | 7 | Apr to Oct | $0 | $283 |
| Heat pump + cover | 7 | Apr to Oct | $273 | $823 |
| Gas heater + cover | 7 | Apr to Oct | $366 | $791 |
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 Fresno
Solar panels + cover: 7 of 7 possible months for about $283 a year all-in, which works out near $94 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 gas as well as a heat pump: once the purchase price is counted, gas comes out cheaper all-in here (heat pump or gas).
Weather station: Fresno Yosemite International, 4 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Fresno 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 | 55° | 48° | 2.4 | 47° | 53° | – | – |
| Feb | 61° | 52° | 3.6 | 51° | 57° | – | – |
| Mar | 68° | 57° | 5.1 | 57° | 63° | – | – |
| Apr | 74° | 62° | 6.5 | 63° | 69° | $209 | $273 |
| May | 83° | 70° | 7.7 | 71° | 77° | $54 | $79 |
| Jun | 91° | 78° | 8.5 | 79° | 85° | – | – |
| Jul | 98° | 84° | 8.1 | 86° | 92° | – | – |
| Aug | 97° | 82° | 7.4 | 87° | 93° | – | – |
| Sep | 91° | 77° | 6.1 | 83° | 89° | – | – |
| Oct | 79° | 67° | 4.5 | 73° | 79° | $10 | $14 |
| Nov | 65° | 55° | 3.1 | 61° | 67° | – | – |
| Dec | 55° | 48° | 2.2 | 51° | 57° | – | – |
Heating costs most in Apr (about $209 with a heat pump, $273 with gas). Sunshine peaks in Jun at 8.5 kWh/m²/day (NASA satellite data, 40.9 km grid cell). Highlighted months are swimmable with no heater.
How Fresno compares with nearby cities
Fresno ranks 24 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 |
|---|---|---|---|---|
| Clovis, CA | 7 mi | 4 | 7 | $273 |
| Sanger, CA | 14 mi | 4 | 9 | $734 |
| Kerman, CA | 15 mi | 3 | 7 | $430 |
| Selma, CA | 18 mi | 4 | 9 | $734 |
| Parlier, CA | 18 mi | 4 | 9 | $734 |
| Madera, CA | 21 mi | 3 | 7 | $376 |