July 12 (Reuters) - Demand for power in Texas hit a record high on Wednesday as homes and business cranked up air conditioners during a lingering heatwave, according to data from the state's power grid operator.

ERCOT said power use reached a preliminary 81,351 megawatts (MW) at 6 p.m. CST (2300 GMT), topping the grid's previous record of 80,828 MW set on June 27.

Peak demand is expected to set another record at 83,454 MW on Thursday.

Meteorologists at AccuWeather forecast high temperatures in Houston, the biggest city in Texas, would hit 100 degrees Fahrenheit (37.8 Celsius) almost every day from July 12-19. That compares with a normal high of 94 F for this time of year.

The Electric Reliability Council of Texas (ERCOT), which operates the grid for more than 26 million customers representing about 90% of the state's power load, has said it has enough resources available to meet the soaring demand.

Texas residents have worried about extreme weather since a deadly storm in February 2021 left millions without power, water and heat for days as ERCOT scrambled to prevent a grid collapse after the closure of an unusually large amount of generation.

One megawatt can power around 1,000 U.S. homes on a typical day, but only about 200 homes on a hot summer day in Texas.

Since mid-June, the grid has projected demand would hit record highs on at least 13 days, but usage has only set an all-time high twice this year.

With the heat building, day-ahead power prices settled at between $100 and $330 per megawatt hour for eight hours for Thursday afternoon. Real-time prices at HB Houston node were at$143 as of 6:30 p.m. CST, after touching $1,372 at 4:30 p.m. CST on Wednesday, according to the ERCOT website.

Next-day or spot prices at the ERCOT North Hub , which includes Dallas, rose more than 200% to hit $123 per megawatt hour for Wednesday. That compares with an average of $33 so far this year, $78 in 2022 and a five-year (2018-2022) average of $66.

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