Pool swim season in Harlingen, TX
Swim season in Harlingen without a heater, and with one
An unheated pool in Harlingen reaches 78°F in May to Oct, about 6 months a year. The air allows up to 12 swimmable months with a heater (all year).
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What each heater buys you in Harlingen
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 6 | May to Oct | $0 | $0 |
| Solar cover only | 8 | Apr to Nov | $0 | $50 |
| Solar panels + cover | 9 | Mar to Nov | $0 | $283 |
| Heat pump + cover | 12 | all year | $323 | $873 |
| Gas heater + cover | 12 | all year | $775 | $1,200 |
For a 450 sq ft pool held at 80°F, at TX prices of 16.0¢/kWh electricity and $19/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Harlingen
Heat pump + cover: 12 of 12 possible months for about $873 a year all-in, which works out near $146 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: Harlingen, 1.7 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Harlingen 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 | 72° | 61° | 3.1 | 62° | 68° | $115 | $266 |
| Feb | 76° | 65° | 3.7 | 64° | 70° | $91 | $223 |
| Mar | 81° | 71° | 4.6 | 70° | 76° | $38 | $100 |
| Apr | 86° | 76° | 5.4 | 76° | 82° | – | – |
| May | 91° | 82° | 6.0 | 82° | 88° | – | – |
| Jun | 95° | 86° | 6.5 | 87° | 93° | – | – |
| Jul | 97° | 87° | 6.5 | 90° | 96° | – | – |
| Aug | 98° | 87° | 6.2 | 90° | 96° | – | – |
| Sep | 93° | 83° | 5.2 | 88° | 94° | – | – |
| Oct | 88° | 77° | 4.6 | 82° | 88° | – | – |
| Nov | 80° | 69° | 3.5 | 74° | 80° | $1 | $3 |
| Dec | 73° | 63° | 2.8 | 66° | 72° | $78 | $183 |
Heating costs most in Jan (about $115 with a heat pump, $266 with gas). Sunshine peaks in Jun at 6.5 kWh/m²/day (NASA satellite data, 39.6 km grid cell). Highlighted months are swimmable with no heater.
How Harlingen compares with nearby cities
Harlingen ranks 12 of 252 Texas cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| San Benito, TX | 5 mi | 6 | 12 | $323 |
| Mercedes, TX | 14 mi | 6 | 12 | $356 |
| Weslaco, TX | 18 mi | 6 | 12 | $356 |
| Brownsville, TX | 19 mi | 6 | 12 | $264 |
| Raymondville, TX | 20 mi | 6 | 12 | $398 |
| Donna, TX | 21 mi | 6 | 12 | $349 |