When Shakira Franklin drives from West Baltimore to her job near the city's Inner Harbor, she can feel the summer heat ease up like a fist loosening its grip.

"I can actually feel me riding out of the heat. When I get to a certain place when I'm on my way, I'll turn off my air and I'll roll my windows down," says Franklin. "It just seems like the sun is beaming down on this neighborhood."

Franklin isn't imagining that. Her neighborhood, Franklin Square, is hotter than about two-thirds of the other neighborhoods in Baltimore — about 6 degrees hotter than the city's coolest neighborhood. It's also in one of the city's poorest communities, with more than one-third of residents living in poverty.

Across Baltimore, the hottest areas tend to be the poorest and that pattern is not unusual. In dozens of major U.S. cities, low-income neighborhoods are more likely to be hotter than their wealthier counterparts, according to a joint investigation by NPR and the University of Maryland's Howard Center for Investigative Journalism.

Those exposed to that extra heat are often a city's most vulnerable: the poorest and, our data show, disproportionately people of color. And living day after day in an environment that's literally hotter isn't just uncomfortable, it can have dire and sometimes deadly health consequences — a fact we found reflected in Baltimore's soaring rates of emergency calls when the heat index spiked to dangerous levels.

According to a Howard Center analysis of U.S. census data and air temperature data obtained from Portland State University and the Science Museum of Virginia, the hottest neighborhoods in Baltimore can differ by as much as 10 degrees from the coolest.

Read the full article about rising temperatures by Sean McMinn and Meg Anderson at NPR.