Swath of Texas swelters in record-setting spring heat wave

By Steve Gorman

(Reuters) - Large swaths of central and south Texas sweltered for a second day under a record-setting springtime heat wave on Thursday, as forecasters warned residents of the region to stay hydrated and limit strenuous outdoor activities.

The National Weather Service posted heat advisories across 15 Texas counties stretching from the Rio Grande and Texas Hill Country to the Gulf of Mexico where temperatures were climbing 15 to 20 degrees Fahrenheit (8 to 11 degrees Celsius) above normal into the upper-90s and triple-digit readings Fahrenheit (upper 30s Celsius).

An area of central Texas encompassing San Antonio and the state capital of Austin was expected to see heat-index values - a measure of how warm it feels with air temperatures and relative humidity combined - running as high as 109 degrees F (42.7 C).

The heat index was forecast to reach 110 F in the border town of Laredo on the Rio Grande and to top out at 112 F (44.4 C) in the oil field hub of Alice, inland from Corpus Christi.

Houston was expected to feel almost brisk by comparison with a maximum heat index expected at 101 F.

The 100-degree peak air temperature recorded on Wednesday at Austin-Bergstrom Airport marked an all-time high for that date, and forecasters said Thursday's daily record, 96 degrees F in 2003, was expected to be shattered as well.

The Weather Service said more high heat and humidity were in store through the weekend and into early next week, with sauna-like conditions expected to crest on Friday.

While no single extreme-weather event can be easily attributed to global warming, scientists generally agree that episodes of unseasonably high temperatures are becoming more frequent, prolonged and pronounced as a consequence of climate change.

To prevent heat exhaustion or heat stroke, residents were urged to avoid over-exertion outdoors, run their air-conditioning indoors, drink plenty of fluids and wear lightweight clothing.

The torrid Texas weather was part of a larger dome of above-average heat building over large stretches of the U.S. from the central and southern Plains east to the Atlantic coast into Florida, according to forecasters.

(Reporting by Steve Gorman in Los Angeles; Editing by Sandra Maler)