Pool swim season in Marshall, TX
When can you swim in an outdoor pool in Marshall, TX?
An unheated pool in Marshall 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 Marshall
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 4 | Jun to Sep | $0 | $0 |
| Solar cover only | 4 | Jun to Sep | $0 | $50 |
| Solar panels + cover | 6 | May to Oct | $0 | $283 |
| Heat pump + cover | 7 | Apr to Oct | $161 | $711 |
| Gas heater + cover | 7 | Apr to Oct | $393 | $818 |
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 Marshall
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.
A solar cover alone adds no swim months here, so if you want a longer season you need a heater (why); still use one at night to hold the heat you pay for. 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: Marshall, 3.7 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Marshall 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° | 45° | 2.7 | 46° | 52° | – | – |
| Feb | 62° | 49° | 3.1 | 47° | 53° | – | – |
| Mar | 69° | 56° | 4.3 | 54° | 60° | – | – |
| Apr | 76° | 64° | 5.4 | 62° | 68° | $110 | $263 |
| May | 83° | 72° | 5.9 | 71° | 77° | $29 | $77 |
| Jun | 90° | 79° | 6.4 | 79° | 85° | – | – |
| Jul | 94° | 82° | 6.4 | 84° | 90° | – | – |
| Aug | 94° | 82° | 6.0 | 85° | 91° | – | – |
| Sep | 88° | 76° | 5.1 | 81° | 87° | – | – |
| Oct | 78° | 65° | 4.1 | 72° | 78° | $22 | $53 |
| Nov | 67° | 55° | 3.0 | 60° | 66° | – | – |
| Dec | 59° | 47° | 2.5 | 50° | 56° | – | – |
Heating costs most in Apr (about $110 with a heat pump, $263 with gas). Sunshine peaks in Jul at 6.4 kWh/m²/day (NASA satellite data, 14.4 km grid cell). Highlighted months are swimmable with no heater.
How Marshall compares with nearby cities
Marshall ranks 238 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 |
|---|---|---|---|---|
| Longview, TX | 24 mi | 4 | 8 | $277 |
| Kilgore, TX | 31 mi | 4 | 7 | $106 |
| Shreveport, LA | 33 mi | 4 | 8 | $221 |
| Henderson, TX | 37 mi | 4 | 7 | $125 |
| Bossier City, LA | 41 mi | 4 | 8 | $202 |
| Mount Pleasant, TX | 56 mi | 4 | 7 | $187 |