Hot topic: This is why Phoenix sees such extreme heat in the summer

PHOENIX — There’s nothing like record-breaking heat to have people around the country asking this question: Why does it get so hot in Phoenix?

Before you go there, the answer is far more complex than “It’s a desert. Duh.”

“Desert doesn’t necessarily mean that a place is hot. It means that a place is dry,” meteorologist Paul Iñiguez, the science and operations officer at NOAA National Weather Service in Phoenix, said.

“Actually, the biggest desert on Earth is the Antarctic Desert, which isn’t very hot. It’s very cold at the South Pole.”

However, at least one popular topic — the “dry heat” everyone talks about — is a factor in why Phoenix gets so hot.

“The drier air is, the more easy it is for it heat up and mostly a factor of the moisture,” Iñiguez said. “So if you have more humid air, water takes more energy to heat up.”

That’s why some place at the same latitude as Phoenix, such as an Atlanta, doesn’t get as hot as we do.

Another factor has to do with the number of high pressure systems that roll into the American Southwest.

“The western United States is a location that is more susceptible to more high pressure,” Iñiguez said. “And when we get that high pressure during the summer time, it is sinking air … and as air sinks, it compresses, and it heats up.”

The Valley’s elevation is also a contributing factor to the high summer temperatures. The closer a city is to sea level, the hotter it can get.

“Phoenix is about 1,000 feet in elevation, so we get pretty hot there,” Iñiguez said. “But if you go to a lower elevation — some place like Death Valley obviously being the hottest — we know they’re several hundred feet below sea level, so that’s why they can get much hotter.”

A final factor is called the urban heat island, which is created by the huge sprawling collection of concrete, asphalt, glass and buildings that make up the Valley.

“Those things take in the energy from the sun during the day and then they hold on to them and release it slowly at night,” Iñiguez said.

“Places like downtown Phoenix, they’re going to be much warmer at night because of all the energy that the buildings and the roads hold on to.”

Though it may be hot during the day, the open desert land around the city actually cools quicker at night.

“The desert, the rocks and the dirt out there, they release their energy very quickly back out into space during the nighttime, so they cool down fast,” Iñiguez said.

 

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