In this story, we’re following up on the Charlotte Heat Mappers project we covered this July. Read or listen to that story first here.
This summer, 60 volunteers set out on a hot and humid day in mid-July to map Charlotte’s urban hotspots. The Charlotte Heat Mappers met at the DuBois Center near uptown’s First Ward Park, where morning temperatures were 12 degrees Fahrenheit warmer than nearby, rural Wadesboro, about 50 miles east.
The National Integrated Heat Health Information System analyzed the raw data collected by the heat mappers’ sensors. The volunteers had driven outward from uptown during three shifts — a morning, afternoon and evening shift — covering 100 square miles at a grueling 35 mph max speed. That’s no easy feat, given Charlotte’s famously chaotic roads. (A 2019 study of urban street entropy — basically, how disorganized a city is — found that Charlotte’s disorder ranked highest in the world, with sprawling streets reaching outward in all directions.)
Charlotte Heat Mappers have now released an interactive story map that allows city residents to search addresses and learn how much hotter they are compared to rural reference points at the highest and lowest temperatures throughout the day.
The raw data volunteers collected looked like multi-color, banded worms crawling away from the Dubois Center. A modeling agency filled in the gaps between the routes the volunteers drove with land-use data and aerial imagery.
Katherine Idziorek is a professor of urban design at UNC Charlotte and leader of the Charlotte Heat Mappers. She expected to find Charlotte’s history of underinvestment in low-income, nonwhite communities reflected in the way heat moves through the city.
“We were also thinking that there would be a clearer ‘Crescent and Wedge’ pattern here, but it turns out Charlotte is hot everywhere,” said Katherine Idziorek, an assistant professor of urban planning at UNC Charlotte and leader of the Charlotte Heat Mappers. “Although, it’s definitely hotter in some places than others.”
Some of the hottest: Places like Freedom Drive, Wilkinson Boulevard and North Tryon Street that have wide roads, big box stores and asphalt parking lots. Those paved surfaces soak up energy during the day and slowly radiate heat overnight, raising temperatures and creating Charlotte’s urban heat island. The Charlotte Heat Mappers noticed that effect most in the morning when some neighborhoods were up to 11 degrees hotter than others.
The corridor surrounding the light rail also remained consistently hot throughout the day.
“We have to think about that as we’re developing — how can we make this environment safe and comfortable for people who are biking, walking and using transit?” Idziorek said.
It poses a significant planning challenge in a city that aims to increase mobility for commuters who don’t drive. New railways and bus lanes create more impervious surfaces that make Charlotte a warmer place to live, but it’s the highways and parking lots for commuter vehicles that made the city warm to begin with.
Not all neighborhoods are heated equal
The city’s recent climate risk assessment identified extreme heat as one of the most significant climate-related threats to city residents. High overnight temperatures have a cumulative effect on the body’s ability to cool down during the day, according to the World Health Organization. When the body can’t cool down at night, it becomes more vulnerable to high temperatures during the day.
Idziorek said communities of color and low-income communities tend to be at higher risk of heat exposure, since those neighborhoods tend to have fewer open, green spaces and trees and more paved areas. The federally-funded heat mapping project was part of the Justice 40 initiative, designed to provide data to help underresourced communities.
Persistent heat brings financial burdens, as hotter communities spend more money on cooling during the summer.
The map also highlights Charlotte’s coolest areas: country clubs, golf courses, nature preserves and urban forests. Neighborhoods like Marlwood Acres in east Charlotte stayed cooler.
“The houses are relatively small, there’s a lot of green buffer in between them, and so these are areas where the trees are doing a lot to cool the temperatures,” Idziorek said. “You can see that those parks and greenways are doing that work to cool the city down.”
How does your neighborhood stack up? You can let the Charlotte Heat Mappers know if their map matches up with your heat experience in the city by emailing heatmappers@charlotte.edu.
