First real heat wave to hit Valley bringing dangerous temps

The Rio Grande Valley is in for dangerously hot temperatures this week through Thursday, according to the National Weather Service Brownsville-RGV station.

The first official first day of summer is still six weeks away. Still, May 9 is likely to see record high temperatures across deep South Texas, according to NWS meteorologists, who warned that very warm temperatures combined with high humidity will push heat-index values well over 100 degrees, probably more toward 110 degrees and close to 115 degrees in some locations.

Heat index is a calculation, based on actual temperature and relative humidity, that indicates how hot the air actually feels. Heat index is also referred to as “feels like” temperature.

“A strengthening ridge of high pressure will continue to build northward through mid to late week, further intensifying the above average temperatures we’ve experienced over the past few days,” the NWS said. “The combination of very warm temperatures and elevated relative humidity will lead to dangerous heat (indexes) … Tuesday, Wednesday and Thursday.”

For Tuesday, maximum head indexes were expected to range from 107 to 114 degrees for the western half of deep South Texas, though the numbers could be lower depending on the amount of cloud cover, meteorologists said. Wednesday and Thursday, the eastern half of the region can expect maximum heat indexes of around 112 to 115 degrees, with limited relief overnight with heat indexes dropping only to about 57 to 82 degrees, according to NWS.

“Ambient temperatures (maximum temperatures minus relative humidity) may be even hotter than the heat indices Wednesday and Thursday for portions of the Upper Rio Grande Valley and western ranch lands,” said the agency. “There are above-average chances that record high temperature (records) will be broken Wednesday and Thursday.”

Meteorologists warned that people unprepared for heat indexes of 111 to 115 degrees can easily suffer from heat exhaustion, while heat stroke is a serious risk for people exposed to heat for several hours without adequate protection.

“Heat stroke is likely, and death possible, to persons exposed to the ‘feels like’ temperatures of 116 or higher,” the NWS said.

Vital precautions when dealing with dangerous heat include “look before you lock,” or in other words, make sure there are no small children or pets in your car when you lock it.

Also, always stay hydrated, take frequent breaks in the shade when working outdoors, wear lightweight, loose-fitting clothing, save strenuous exercise for the early morning hours (less strenuous exercise for sunset and one hour afterward), and check on the elderly and move them into air conditioning immediately.

Children and pregnant women also are at higher risk in extreme heat, the NWS said, noting that pets should be moved indoors to cooler areas “until the heat is manageable.”

“Heat (indexes) exceeding 110 degrees may have a life-threatening impact on border operations,” the agency said. “Border Patrol, law enforcement and people being monitored must be hydrated and remain in shaded areas as long as possible during this brief heatwave.”

The forecast range for McAllen is 98 to 108 Wednesday and 100 to 112 Thursday. Brownsville will see temperatures between 93 and 99 on Wednesday and 97 to 106 Thursday. For Harlingen, the forecast temperature range is 96 to 103 Wednesday and 98 to 111 Thursday, according to the NWS.

Meteorologists said the wide temperature range in each case indicates a degree of uncertainty due to the effect of “varying cloud, a passing front or other related weather conditions.”

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