Dr. Ryan Bare and Qian Song
Houston just emerged from a week of 100-degree temperatures, and with nearly another month left of summer, the region’s tolerance for heat is not done being tested for the year.
We know from our 2024 heat mapping campaign there can be as much as a 14-degree difference between two neighborhoods. But how heat affects the urban landscape also depends on other factors, such as time of day and heat persistence.
Some neighborhoods begin the morning warmer. Others remain hotter than average throughout the afternoon. Some hold onto heat long after the sun begins to set.
When all these differences are considered, some neighborhoods clearly face disproportionate heat exposure.
HARC’s Heat Burden Priority Index, based on the concept of the Triple Heat Threat, integrates these differences, providing a more complete picture of how heat is experienced across the urban environment.
The index incorporates three dimensions, based on data collected by 150 volunteers in the morning, at midday and in the evening on Aug. 10, 2024:
When applied across the priority areas that were mapped in 2024, we identified 19 neighborhoods that were experiencing this triple threat more than others: Magnolia Park, OST / South Union, Gulfgate Riverview / Pine Valley, Briar Forest, Uptown, Pecan Park, Gulfton, Harrisburg / Manchester, Mission Bend, Sharpstown, South Acres / Crestmont Park, Mid-West, Four Corners, South Houston, Minnetex, Eastwood, South Park, Spring Branch North, and Pleasantville
Of these, only five also recorded peak temperatures that put them in the top 10 hottest neighborhoods in 2024 – a clear suggestion that the index is capturing a more nuanced picture of heat exposure across the city.
Our study focused on areas with higher concentrations of socioeconomic vulnerabilities – so we can’t definitively say that these are objectively the only areas facing the Triple Heat Threat in Harris County. But the core lesson remains true: Heat is localized, and the built environment matters.
The ability for neighborhoods to release stored heat can influence how residents experience heat throughout the entire day. Unfortunately, many of these 19 neighborhoods aren’t equipped to adequality handle heat, which shows up in our work analyzing tree canopy patterns.
Areas with extensive pavement, limited vegetation, and dense development patterns absorb and retain heat more. This means they stay warmer longer, hours after peak temperatures have passed. There’s a direct line between the health of a neighborhood’s tree canopies and its heat resilience. Magnolia Park, for example – the highest ranking on our heat priority index – has lost 48 acres of tree canopy since 2018.
In addition to their built environments, the 19 neighborhoods we identified also differ in their ability to withstand heat’s effects.
Just consider household economics – South Park’s median household income of $34,883 means its residents may not have the same wherewithal to run an air conditioner 24 hours a day as the typical Harris County household, which has a median income of about $75,000.
Persistent heat also makes it much more difficult for people who work outdoors to get relief. Since April 1, 2026, over 2,500 people have been hospitalized in Harris, Fort Bend and Montgomery counties because of heat-related illness, and that’s in a year that actually hasn’t seen many record-breaking heat days.
Understanding neighborhood heat conditions, the built environment and the community’s social and demographic characteristics can support better targeted planning decisions and policy measures, such as Houston’s recent move to require air conditioning in rental properties.
Neighborhoods do not need to record the highest afternoon temperature to experience significant heat burden. Remaining warmer throughout the day, beginning the morning at elevated temperatures, or exhibiting a combination of multiple heat-related conditions are critical to consider when designing a mitigation strategy.
Just as urban forestry has evolved beyond simply counting trees, heat planning must evolve beyond identifying the highest temperatures. Considering heat data to inform planting efforts, particularly where heat intersects with economic disadvantages, can optimize the cooling benefit of tree plantings.
By investing in data-informed tree planting and other heat mitigation efforts, Houston could directly improve the quality of life for Houstonians who live in heat-burdened areas.