The head of the National Weather Service calls it a heat wave longer than any he can remember, and nowhere is it being felt as intensely as in Dallas, Texas, where Thursday marked the 34th day of triple-digit temperatures.

Dallas is also well on its way to breaking its record of 42 straight days at 100 or above, set in 1980. The Weather Channel's forecast through Aug. 13, which would be day 43, shows no day with a high below 102 degrees.

So how rough is this heat wave compared to ones in recent summers?

"I can't remember any year with the magnitude and length of this heat wave," Jack Hayes, director of the National Weather Service, told msnbc.com on Thursday.

And it's not just Dallas, or even Texas, for that matter. On Thursday, 14 states from Texas to Virginia were under heat alerts. Several dozen deaths have been tied to the heat since early July.

Though it is hot across much of the South, the "bull's-eye" of the heat is being felt in Oklahoma, Arkansas, Texas and Louisiana, said National Weather Service meteorologist Joe Jurecka.

Little Rock, Ark., which hit an all-time record high of 114 degrees on Wednesday, faces another stifling 108-degree high on Thursday, Jurecka said.

Additional cooling shelters have opened to help the nearly 4,000 people without power after a breaker malfunction caused by a fire at an Entergy substation in Benton, Ark., about 20 miles southwest of Little Rock.

There is little relief expected from the heat wave across the region, even after the sun goes down, Jurecka said.

"One thing that really causes this to stand out is the nighttime lows are much higher in this outbreak," he said, comparing the current hot spell to a similar one in 1980.

"It doesn't cool down. That puts additional overnight strain on everything."

On Tuesday and Wednesday, all-time heat records were set at 15 cities and towns, mostly in the South and central U.S., National Weather Service statistics show. That's preliminary data based on just half of the weather stations across the U.S., so the number's likely to be higher when all stations are counted.

In July, 49 all-time records were set and 29 were tied, according to preliminary data. That's well above the average over the previous decade.

Four times as many records did fall in 2002, but that year includes all weather stations and most records were broken in relatively cooler and less populated areas of the Northwest and Southwest.

Most of the records broken last month were in the Northeast, which has since seen cooler temperatures, and the South, which continues to bake.

As for coming months, the U.S. Climate Prediction Center on Thursday said the La Nina weather conditions that contributed to the drought affecting most of Texas may re-occur later this year and prolong the misery for the state's farmers and ranchers.

The last La Nina ended about two months ago. The weather pattern is marked by a cooling of the tropical Pacific Ocean and it typically results in less rain for southern states.

La Nina contributed to the worst drought in Texas history, in the 1950s. Nearly three-quarters of the state is currently in what the U.S. Drought Monitor classifies as the worst stage of drought.

The Climate Prediction Center is calling for neutral conditions through fall but "neutral or La Nina equally likely thereafter." (Source: MSNBC)

Story Date: August 5, 2011