Here's how much hotter the urban heat island effect makes metro Phoenix

The extreme temperatures Phoenix residents are feeling right now are made even hotter by all of the asphalt and concrete absorbing heat across the metro area.

A new study on the urban heat island effect from the climate research group Climate Central finds the built environment and population density of the Phoenix area amplify temperatures by about 7.4 degrees, on average. That’s actually less of an urban heat island effect than many other U.S. cities experience.

“We tend to find a lot of difference between the traditional Northern city – which is very densely packed, lots of big buildings in the middle, lots of people living in that city core – and a lot of Southern cities that are a little more distributed,” said Climate Central senior data analyst Jen Brady. “And what that does is it does break up the heat a bit because you don't have so many factors all in one place that elevate the heat.” 

But Brady said the health risks of additional urban heat are higher in Phoenix.

“On top of an already very high temperature, seven and a half degrees can really be a breaking point,” Brady said.

Researchers analyzed land cover and population density for census block groups across 65 U.S. cities to estimate the severity of urban heat island effects.

“It's the combination of the brick, the stone, the pavement that's absorbing heat, holding heat. How much of that is in the environment? How many people are in the environment? And that's going to give you a good representation of how much additional heat is in that area,” Brady said.

In Maricopa County, Climate Central’s Census tract-level U.S. map shows the urban heat island effect is most pronounced in downtown Phoenix, and parts of Scottsdale and Tempe, where temperatures are more than nine degrees hotter than surrounding rural areas.

Researchers recommend cities invest in trees, green spaces and other shade solutions to mitigate the effects of urban heat.

“We're hoping what people really do is look at their city and say, ‘Where are the problems in our city? And how can we make those areas better?’” Brady said.