Heat Wave: Soaring Temperatures Spread Across U.S.

July 13, 2011— -- The death toll from the heat wave stretching across the U.S. rose to 39 today as scorching temperatures have affected nearly half of the country's population.

Some 150 million people are being seared by the relentless heat that has shattered records and led the National Weather Service to issue heat warnings for 24 states. Record temperatures across the country were either matched or broken at least 670 different times since the beginning of July.

In Wisconsin, 15 runners were hospitalized after collapsing during a half marathon.

"Your brain cannot function at temperature extremes, and so if you get too hot, you can have problems and you can have long- term damage," Dr. David Messerly of Rex Hospital in Raleigh, N.C., told ABC News.

This week Oklahoma City saw its hottest temperatures in 20 years, at 111 degrees. Tuesday was the city's 14th straight day above 100 degrees.

In Union County, S.C., fans were being handed out to the public, but the supply ran out.

"It concerns me because there are people out there who are suffering, when something as small as a $15 fan can make a difference in their lives," Lynn Smosky of the Council for Aging in Union City, told ABC News.

Phoenix has seen at least 33 consecutive days of temperatures at or above 100 degrees, while Dallas has seen at least 11 consecutive days with temperatures at or topping 100. Dallas city Inspectors are going door-to-door to ensure that air conditioners are working.

Medical experts say drinking plenty of water is the best line of defense.

"When the heat goes up at this level, you could be going through a liter every hour. If you don't replace that, it could be very dangerous," ABC News' chief health and medical editor Dr. Richard Besser said.

High Temperatures, Drought Affecting Farms

Drought is now gripping farms and ranch lands in the South and Southwest, with parts of Texas breaking drought records set in 1917. The federal government has declared the entire state a disaster area, with an estimated $3 billion in agricultural losses.

With temperatures in Oklahoma and Texas as high as 105 degrees, and draught so bad, cattle farmers have to make difficult decisions.

Ranchers in Tulsa, Okla., were selling what they would normally keep – with no rain there is no hay to feed the cattle. This will mean that beef prices will be on the rise.

"We can expect higher prices in the future, on top of what are already record retail prices for consumers," David Anderson, livestock economist from the Texas Agri-Life Extension Service, told ABC News.