Pool swim season in Ennis, TX
When can you swim in an outdoor pool in Ennis, TX?
An unheated pool in Ennis 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 Ennis
| 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 | 6 | May to Oct | $0 | $283 |
| Heat pump + cover | 7 | Apr to Oct | $125 | $675 |
| Gas heater + cover | 7 | Apr to Oct | $309 | $734 |
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 Ennis
Solar panels + cover: 6 of 7 possible months for about $283 a year all-in, which works out near $142 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 a heat pump sized to your pool's surface area; here it beats gas all-in (heat pump or gas).
Weather station: Bardwell Dam, 4.3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Ennis 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° | 46° | 2.9 | 47° | 53° | – | – |
| Feb | 61° | 50° | 3.3 | 49° | 55° | – | – |
| Mar | 68° | 57° | 4.4 | 55° | 61° | – | – |
| Apr | 75° | 65° | 5.4 | 63° | 69° | $100 | $243 |
| May | 82° | 73° | 5.8 | 72° | 78° | $21 | $55 |
| Jun | 90° | 81° | 6.7 | 81° | 87° | – | – |
| Jul | 94° | 84° | 6.7 | 86° | 92° | – | – |
| Aug | 95° | 84° | 6.2 | 87° | 93° | – | – |
| Sep | 89° | 78° | 5.2 | 83° | 89° | – | – |
| Oct | 79° | 67° | 4.1 | 74° | 80° | $4 | $11 |
| Nov | 67° | 56° | 3.1 | 62° | 68° | – | – |
| Dec | 59° | 48° | 2.6 | 52° | 58° | – | – |
Heating costs most in Apr (about $100 with a heat pump, $243 with gas). Sunshine peaks in Jul at 6.7 kWh/m²/day (NASA satellite data, 23.2 km grid cell). Highlighted months are swimmable with no heater.
How Ennis compares with nearby cities
Ennis ranks 162 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 |
|---|---|---|---|---|
| Waxahachie, TX | 13 mi | 4 | 7 | $138 |
| Red Oak, TX | 15 mi | 4 | 7 | $138 |
| Corsicana, TX | 19 mi | 4 | 7 | $127 |
| Glenn Heights, TX | 20 mi | 4 | 7 | $138 |
| Lancaster, TX | 20 mi | 4 | 7 | $115 |
| Midlothian, TX | 23 mi | 4 | 7 | $138 |