PHOENIX — How's that electricity bill looking? High from running your AC all the time? What about your pool? Is it like bathwater? When was the last time you opened a window? We're used to scorching hot days ... But boiling nights? Not so much.
Phoenix isn't cooling off after the sun goes down, and that's a problem.
July saw the hottest overnight low temperature ever recorded in Phoenix: 90.8 degrees Fahrenheit. Overnight lows have been steadily increasing since we started collecting data in 1895. But they really started to climb in the 70s, when paving over the Valley became all the rage.
It's called an "urban heat island," and here's a look at what it does to our overnight temperatures:
"Asphalt, concrete and cement (like in roads and buildings) store sunlight during the day and release the heat slowly at night. Buildings and roads cool off very slowly at night, which means that air temperatures in the city cool off very slowly at night. Daytime (maximum) air temperatures are usually not as impacted by this process, but nighttime (minimum) air temperatures increase as urbanization increases," the Arizona State Climate Office explained.
Phoenix has one of the most severe urban heat islands in the world, with a roughly 10-14 degree difference between our recording station at Sky Harbor Airport and surrounding rural communities.
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That's why summer feels worse lately, because as the climate office says, "the urban heat island is usually at its largest magnitude during calm, dry, summer nights."
With monsoon rain scarce this year, those nights are all we're getting.
HEAT BEAT
Here are several videos about Arizona's extreme heat and how you can stay safe during the state's summer months.