Pool swim season in Terrell, TX
Swim season in Terrell without a heater, and with one
An unheated pool in Terrell 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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What each heater buys you in Terrell
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 4 | Jun to Sep | $0 | $0 |
| Solar cover only | 6 | May to Oct | $0 | $50 |
| Solar panels + cover | 7 | Apr to Oct | $0 | $283 |
| Heat pump + cover | 7 | Apr to Oct | $107 | $657 |
| Gas heater + cover | 7 | Apr to Oct | $264 | $689 |
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 Terrell
Solar cover only: 6 of 7 possible months for about $50 a year all-in, which works out near $25 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: Terrell Municipal Airport, 1.9 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Terrell 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 | 57° | 47° | 2.9 | 47° | 53° | – | – |
| Feb | 62° | 51° | 3.3 | 49° | 55° | – | – |
| Mar | 69° | 58° | 4.4 | 56° | 62° | – | – |
| Apr | 76° | 65° | 5.4 | 64° | 70° | $93 | $227 |
| May | 84° | 74° | 5.8 | 72° | 78° | $14 | $37 |
| Jun | 92° | 81° | 6.7 | 81° | 87° | – | – |
| Jul | 96° | 85° | 6.7 | 87° | 93° | – | – |
| Aug | 96° | 85° | 6.2 | 88° | 94° | – | – |
| Sep | 90° | 78° | 5.2 | 84° | 90° | – | – |
| Oct | 79° | 68° | 4.1 | 74° | 80° | – | – |
| Nov | 68° | 57° | 3.1 | 62° | 68° | – | – |
| Dec | 59° | 48° | 2.6 | 52° | 58° | – | – |
Heating costs most in Apr (about $93 with a heat pump, $227 with gas). Sunshine peaks in Jul at 6.7 kWh/m²/day (NASA satellite data, 31.4 km grid cell). Highlighted months are swimmable with no heater.
How Terrell compares with nearby cities
Terrell ranks 87 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 |
|---|---|---|---|---|
| Forney, TX | 9 mi | 4 | 7 | $107 |
| Heath, TX | 13 mi | 4 | 7 | $165 |
| Seagoville, TX | 15 mi | 4 | 7 | $115 |
| Rockwall, TX | 16 mi | 4 | 7 | $165 |
| Fate, TX | 16 mi | 4 | 7 | $165 |
| Mesquite, TX | 17 mi | 4 | 7 | $74 |