Dangerous heat bursts have been spiking temperatures across the US as people sleep. So what are they?

Yahoo

26-05-2025

An intense burst of heat hit southwestern Oklahoma on Sunday, sending temperatures spiking into the high 90s.
In the city of Chickasha, which is located approximately 40 minutes from Oklahoma City, the weather event occurred in the early morning hours.
'Several hit southwest Oklahoma this morning. An intense burst of extreme heat hit Chickasha, Oklahoma at 5:15 a.m. Sunday morning, bringing the temperature to 95.6 degrees!' meteorologist and atmospheric scientist Matthew Cappucci wrote on the social media platform X.
But, what are heat bursts and how do they form? Here's what you should know.
Heat bursts are localized and sudden increases of temperature that are associated with a thunderstorm.
The relatively rare atmospheric nighttime events are often accompanied by 'extreme drying,' according to the American Meteorological Society Glossary of Meteorology.
They're also characterized by gusty winds.
'Chickasaw went from 77 degrees and 80 percent relative humidity to 95.6 degrees and just 17 PERCENT humidity!' Cappucci noted. 'Chickasaw also gusted to 59 mph! Medicine Park, Oklahoma warmed to 81.2 degrees and gusted to 69 mph. Altus got to 89 degrees shortly after 2 a.m.'
Heat bursts need a dissipating thunderstorm or shower and a hot and dry midlevel atmospheric environment to form, according to National Weather Service forecasters. The midlevel atmosphere is around 20,000 feet above the Earth's surface.
Thunderstorms develop when moist and unstable air is pushed upward, and rain then falls from the storm. When the storm loses that upward moving current of air, it is dominated by a downward moving current of air.
Along with the combination of a hot and dry midlevel atmospheric environment, the downward current's moisture evaporates and cools the midlevel atmospheric layer, increasing its rate of descent toward the ground. The descending air will stop cooling when all the moisture has evaporated, warming the midlevel layer.
The heat burst occurs when the warm and dry air descends to the surface.
'As air sinks, it warms up (and dries out). And if you have an air pocket coming from high enough, it warms up a LOT by the time it reaches the surface. It also brings strong dry winds – like a desert hurricane,' Cappucci noted.
Heat bursts typically occur in the spring and summer, when thunderstorm activity is associated with daytime heating.
While thunderstorms dissipate during the evening as they lose their main source of energy, heat bursts occur in the evening or overnight hours.
They can occur in many regions, but are most common in the Midwest and Plains states. However, they have previously occurred outside of that range. A significant weather event in 2012 brought one to Georgetown County, South Carolina. They've also struck the Southwest.
Climate change is making heat events more frequent and severe.
The rapid increase in surface temperatures - sometimes occurring in less than an hour and leading to a triple-digit high - can take residents by surprise. So can the associated winds, have been known to exceed 70 or 80 mph. They can rip the roofs off buildings and damage trees.
In Chickasha, they knocked out the power for more than 2,000 residents in Grady and Caddo counties, according KOCO 5.