Pool swim season in Ceres, CA
Ceres, CA: how long the pool season really is
An unheated pool in Ceres reaches 78°F in Jul to Sep, about 3 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 Ceres pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 3 | Jul to Sep | $0 | $0 |
| Solar cover only | 4 | Jun to Sep | $0 | $50 |
| Solar panels + cover | 7 | Apr to Oct | $0 | $283 |
| Heat pump + cover | 7 | Apr to Oct | $381 | $931 |
| Gas heater + cover | 7 | Apr to Oct | $504 | $929 |
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 Ceres
Solar panels + cover: 7 of 7 possible months for about $283 a year all-in, which works out near $71 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: Modesto Airport, 2 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Ceres 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 | 56° | 48° | 2.3 | 47° | 53° | – | – |
| Feb | 62° | 52° | 3.5 | 50° | 56° | – | – |
| Mar | 68° | 57° | 4.9 | 56° | 62° | – | – |
| Apr | 74° | 61° | 6.3 | 62° | 68° | $234 | $301 |
| May | 82° | 68° | 7.6 | 69° | 75° | $90 | $126 |
| Jun | 90° | 75° | 8.4 | 77° | 83° | – | – |
| Jul | 95° | 79° | 8.2 | 82° | 88° | – | – |
| Aug | 94° | 78° | 7.4 | 83° | 89° | – | – |
| Sep | 89° | 74° | 6.0 | 79° | 85° | – | – |
| Oct | 79° | 65° | 4.4 | 71° | 77° | $57 | $77 |
| Nov | 66° | 55° | 2.9 | 60° | 66° | – | – |
| Dec | 56° | 47° | 2.1 | 50° | 56° | – | – |
Heating costs most in Apr (about $234 with a heat pump, $301 with gas). Sunshine peaks in Jun at 8.4 kWh/m²/day (NASA satellite data, 42.7 km grid cell). Highlighted months are swimmable with no heater.
How Ceres compares with nearby cities
Ceres ranks 98 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 |
|---|---|---|---|---|
| Modesto, CA | 3 mi | 3 | 7 | $385 |
| Turlock, CA | 9 mi | 3 | 7 | $322 |
| Riverbank, CA | 9 mi | 3 | 7 | $381 |
| Oakdale, CA | 13 mi | 3 | 7 | $381 |
| Patterson, CA | 13 mi | 3 | 7 | $385 |
| Ripon, CA | 13 mi | 3 | 7 | $390 |