(NEWSnet/AP) — Scorching heat blamed for at least 13 deaths in Texas and another in Louisiana blanketed more of the Southeast on Wednesday.

California, meanwhile, was facing its first major heat wave of the year. The National Weather Service warned that the dry, hot, windy conditions were ripe for dangerous fires in parts of Texas, New Mexico, Arizona, Colorado and Utah.

Mid-week temperatures were forecast to surpass 100 degrees in much of the Southeast and high humidity was expected to push heat index values above 115 degrees in some areas.

Lingering power outages after weekend storms compounded the heat-related misery in Arkansas. More than 10,000 residents were still without power in the central part of the state. 

Among the heat's casualties was a man who died late Sunday in Shreveport, Louisiana, the second heat-related death in the state in an unusually warm June.

Eleven of the Texas heat-related deaths occurred in Webb County, which includes Laredo. The dead ranged in age from 60 to 80 years old and many had underlying health conditions, according to Webb County Medical Examiner.

Two Florida hikers also died while hiking in extreme heat at Big Bend National Park.

The heat has prompted the U.S. Postal Service to allow earlier starting times for letter carriers, according to the National Association of Letter Carriers Lonestar Branch. This comes after the death of a letter carrier who died June 20 in near triple-digit heat. The cause of the carrier's death was still under investigation Wednesday.

The unusually high temperatures were brought on by a heat dome that has taxed the Texas power grid and brought record highs to parts of the state, according to meteorologists.

That dome is spreading eastward and by the weekend is expected to be centered over the mid-South.

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