NASA satellite image of a heat wave.
Heat Wave Satellite image of a heat wave. © NASA


Houston/Harris County Holds Largest Single-day, Community-led Heat Mapping Effort in U.S. History

Heat Watch mapping project will inform future climate mitigation strategies and interventions in the urban "hot spots" that need them most.

On August 7, right around when temperatures tend to hit their peak in Houston and Harris County, roughly 75 community scientists will take to the streets with specially-designed thermal sensors attached to their cars or bicycles. They will embark on a 300-square-mile effort to measure and map urban heat in the region. This community science endeavor is led by the Houston Harris Heat Action Team (H3AT), a collaboration between The Nature Conservancy of Texas (TNC), Houston Advanced Research Center (HARC), the City of Houston, and Harris County Public Health (HCPH), and in partnership with Lowe’s and Shell. 

Houston and Harris County are currently facing a number of intersected climate resilience and health challenges—and one of the most significant, yet largely overlooked, is urban heat. Even for a Houstonian, it’s easy to think first of flooding or hurricanes when it comes to regional climate impacts, but increases in daytime and nighttime temperatures at the rate we’ve seen since the 1970s can do as much—if not more—damage.

“Houstonians do not prepare for heat like we prepare for hurricanes, but we should,” said Mayor Sylvester Turner. “Houston is getting hotter, and we need science and data to help identify where the greatest impacts are, so we can keep Houstonians safer and our City more resilient. I thank Heat Watch, Lowe’s, Shell, and the Houston Harris Heat Action Team for partnering to do this extremely important work in our community.”

The urban heat island mapping campaign is included in Resilient Houston, the City’s comprehensive resilience strategy, as part of its commitment to making Houston neighborhoods greener and cooler.    

Heat is the number one weather-related cause of death in the world. It leaves vulnerable communities susceptible to the dangers of stress and stroke, leads to higher ozone levels, and reduces the quality of life for all residents of the region—creating especially dangerous conditions for communities already striving to overcome historic obstacles around access and resources, as well as those who engage in outdoor work and recreation. It makes living in urban environments less and less affordable; it adversely affects our wild neighbors; and—most critically—it shows no sign of stopping.

“With summer in full force, extreme heat and humidity pose a health risk for Harris County residents,” said Jessica Abbinett, Climate Program Coordinator at Harris County Public Health. “Due to the current situation with COVID-19, more residents are spending time staying home, which is a heat safety concern in households without air-conditioning or in households limited by air-conditioning cost.”

Last August was the second warmest on record in Houston, with seven days in a row topping 100 degrees. In fact, all but two days that month met or exceeded the average daily high, leading the power grid to set an all-time record for system peak demand. And as the climate changes and the city expands, these heat-related challenges continue to be exacerbated. Summer heat in Houston is already up to 13 degrees hotter than in nearby rural areas—with communities that lack access to green space bearing the brunt of the impacts—and if there is no reduction in global greenhouse gas emissions, the city can expect the average number of days with a heat index above 105 degrees to increase from 10 to 74 by 2065.

But research shows that there is potential to reshape our built environment and cool our cities down. More and more frequently, local planners and developers are leveraging smart, cooling urban design strategies that offer stacked benefits—including climate resilience—to residents, both human and wild. 

“We have a number of nature-first solutions in our toolkit that can help us cool our cities, but the first step in combating climate- and infrastructure-caused urban heat is to know exactly where to start,” said Jaime González, Houston Healthy Cities Program Director at The Nature Conservancy in Texas. “Once we have a detailed map of Houston’s heat, we’re able to be targeted when it comes to identifying where we should plant trees, install green rooftops, and push forward other heat mitigation tactics that also help support biodiversity, increase access to green space, and clean our air at the very same time.”

Essentially, by developing highly detailed maps that identify where, on a granular level, heat is located and where it’s the most severe, it becomes possible to identify where the implementation of heat mitigation tactics will have the greatest impact. And that type of neighborhood-by-neighborhood mapping is exactly what the H3AT team is rolling out this August.

Using a national protocol, the Houston-Harris County team is leading the largest, single-day, community-led heat mapping effort in history to develop neighborhood-by-neighborhood temperature maps of the region. These maps will help the City of Houston, Harris County, and other climate-minded organizations design future projects and policies that will address heat-related health issues across the region in the most impactful way. The data collected as part of this project will be published on an open-source platform, so that it is accessible to all who want to leverage it. 

“Ultimately, the urban heat island effect can impact many aspects of human health and well-being,” said Dr. Meredith Jennings, Ph.D., Postdoctoral Research Scientist, Resilience. “This study will be an important first step to help communities understand urban heat islands, guide policymakers on next steps, and move forward with science-backed solutions to improve quality of life.”

On August 7, the recruited 'street scientist' volunteers will travel along prescribed routes to record ambient temperatures and humidity at three specific times during the day (6:00-7:00 a.m., 3:00-4:00 p.m., and 7:00-8:00 p.m.). The project volunteers will cover 32 mapping areas, or “polygons,” that each represent a 10-square mile area. 

"Lowe’s is committed to our communities and we are honored to join The Nature Conservancy, City of Houston, HARC, and Harris County Public Health in this project,” says Chris Cassell, Director of Corporate Sustainability at Lowe’s. “Along with our national partners, we’ve rejuvenated Houston neighborhoods, provided aid after natural disasters, and will now help shape the city’s future through environmental data gathering.”

Because this heat mapping project needs to take place on a clear, sunny day, the official date will be contingent on weather. The project partners are working closely with the National Weather Service, and will look at a date during the following week, pending August 7 does not meet the weather specifications.

This project is part of a larger initiative, Heat Watch, led by CAPA Strategies and supported by the National Oceanic and Atmospheric Administration's Climate Program Office, who helped to fund the project. The Houston-Harris County team is one of 13 communities selected to participate in 2020 summer campaigns. For more info, visit CAPA Heat Watch.

The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world's toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at an unprecedented scale, providing food and water sustainably and helping make cities more sustainable. Working in 76 countries and territories: 37 by direct conservation impact and 39 through partners, we use a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit or follow @nature_press on Twitter.