A man walks his bike over the Beach Street bridge at Interstate 30 as the sun sets, Thursday, March 12, 2026, in Fort Worth.
Elias Valverde II/Dallas Morning News
For Dallasites, seeing triple-digit temperatures in the daily forecast lately has become commonplace. In July, every day of the month reached above 90 degrees, and some daily temperatures were as high as 108 degrees.
But one of the most noticeable and alarming changes is that nighttime temperatures are increasing at a higher rate than daytime highs.
Scientists from the University of Texas at Dallas and the University of Texas at Arlington explain why this is the case, and what we can do to slow the trend.
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Why are the lows getting higher?
The increases in daily low temperatures are even more pronounced than those among daily averages, said Xian Wu, assistant professor of climate science at UTD. This is likely due to a combination of increased greenhouse gas emissions and the urban heat island effect in the D-FW area, said Wu.
The urban heat island effect occurs when surfaces that absorb sunlight, buildings that block wind, and a lack of vegetation contribute to cities being hotter than nearby rural areas. Temperatures can vary as much as 12 degrees in some areas due to this effect, according to a study released last April by the city of Dallas.
This effect is at its peak during night, said Arne Winguth, professor of earth and environmental sciences at UTA, when heat trapped during the day by dark surfaces is released back into the air.
Concrete, buildings and roofs, found in abundance in the D-FW area, can all absorb solar radiation during the daytime, Wu said. “After sunset, they slowly release heat, which makes nighttime cooling slower and not very efficient.”
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What can be done to slow this trend?
Although there have only been a few days with temperatures in the triple digits so far this year, high temperatures can be expected to persist well into the coming months, Winguth said.
“Based on the climate model projections for future climate, Texas is going to face more extreme heat and a warmer climate baseline,” Wu said.
One way in which the urban heat island effect can be reduced is by planting more vegetation, Wu said, which can provide more shade and help lower surrounding surface areas. Tree-planting programs in Dallas that have this goal in mind include Branch Out Dallas and Texas Trees Foundation.
“It will be better if we can have more vegetation coverage in the city,” Wu said. Still, she says that lowering greenhouse gas emissions is the best way to reduce the future risks of heat extremes in Texas during both day and night.
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There are several strategies people can use at home to bring down body temperatures during hot nights, said Kristie Ebi, a professor at the University of Washington during a media briefing. Sitting in front of a fan while lightly misting skin with water, soaking feet in cool water, or wrapping a damp towel around the neck can all help people cool down and get through hot nights.
Niamh Ordner is a science reporting fellow at The Dallas Morning News. Her fellowship is supported by the University of Texas at Dallas. The News makes all editorial decisions.