Is Houston now warmer, wetter? Yes and yes
The Houston region has been getting warmer and wetter over the last 30 years while farther south, Galveston has gotten warmer and significantly drier, according to new data released by the National Centers for Environmental Information.
The average mean temperature recorded at Houston’s two airports ticked up slightly over the last three decades, from 69.8 degrees to 70.5 degrees recorded at George Bush Intercontinental/ Houston Airport, and 1 full degree warmer at William P. Hobby Airport, from 70.2 degrees to 71.2 degrees.
Galveston’s 30-year climate data shows that the island has become a regional outlier. While the island’s average regional temperature also increased 1 full degree, from 71.2 degrees to 72.3 degrees, the average annual rainfall fell by more than 3 inches.
Meteorologists who have analyzed the regional data — which also includes College Station — say it shows something of a trend: the closer you get to the Gulf Coast, temperatures increase and rainfall decreases. But also that the 1 degree increase in temperature regionally, while not drastic, underscores widespread evidence and international trends of global warming.
“I think it does validate some of the things from research with
respect to climate change and the Houston area is no exception to that relative to the rest of the country,” said Matt Lanza, a meteorologist who writes for Space City Weather, a go-to source for the region.
The new data was released this month as part of the National Oceanic and Atmospheric Administration’s new climate normals, which give forecasters a way to compare today’s conditions to 30-year averages.
The climate normals update is the equivalent of the Census for those who use the data. The previous climate normals, from 1981–2010 determined the average temperature for the contiguous U.S. was 52.8 degrees while the new average temperature for 1991-2020 is 53.3 degrees, the warmest on record for the country.
Member states of the World Meteorological Organization (WMO) are required to calculate their country’s normals at 10year intervals. Countries follow recommendations by the WMO, which provides a framework for international cooperation among meteorologists, climatologists and hydrologists.
The new data also track rainfall. Overall, the Houston region was significantly wetter over the last 30 years. At Bush Intercontinental Airport, the average annual rainfall increased by 2.07 inches, while Houston Hobby Airport saw a smaller 1-inch average increase.
In Galveston, the spring and summer months saw the sharpest decrease in rainfall, as much as an inch or more fewer than average from April through June. Even this spring, after a couple of weeks of rainy weather, soil moisture levels are well below normal in Galveston, creating drought-like conditions ahead of what could be a scorching summer.
“It’s been drier down there on the coast — Matagorda, Brazoria, Galveston counties — they were in the worst drought this spring up until recently and they’re still in drought down there where most of the inland areas have recovered,” said Jeff Lindner, a meteorologist with the Harris County Flood Control District.
Wendy Wong, a meteorologist for the National Weather Service’s HoustonGalveston office, said the difference with Galveston could be attributed to better data collection, but also unique, unpredictable weather patterns around the barrier island.
“It's an island, so their weather is so much different than the rest of Southeast Texas,” said Wong. “(Galveston’s) more ruled by like tropical systems…. So if there wasn't as many tropical systems, then they probably would not get the rainfall that they had in the past.”
Subtropical high atmospheric pressure over the Gulf of Mexico could partially explain the coastal dryness, Lindner said, protecting the Upper Texas Coast from getting a lot of rain. Subtropical highs have been “very dominant” over the last decade, he added.
But Lindner cautioned against extrapolating too many trends from 30-year averages, noting that sea surface temperatures in the south Pacific Ocean often impact the weather locally.
The Houston-Galveston region was in a serious drought from La Niña (unusually cold Pacific temperatures) in 2011 and 2012, and had major floods in 2015 and 2016 followed by Hurricane Harvey in 2017 from El Niño (unusually warm Pacific temperatures).
“You're going to cycle through these patterns here based on what's happening in the Pacific,” Lindner said. “And so you could have some really big swings, you know, from 2011, which was a horrible drought to 2015, which was horrible flooding.”