Record-breaking August cements summer 2020 as hottest in Phoenix history

July held the crown for the hottest month ever recorded in Phoenix, but its reign didn't last long. 

August quickly took the title for the hottest month on record in Phoenix since tracking began in 1896.

If that's not enough, the unusually hot August pushed 2020 to the unfortunate title of being the hottest summer ever recorded.

August's average of 99.1 degrees surpassed July's in an all-time record average of 98.9 degrees in 2020, according to the National Weather Service in Phoenix.

"Typically July is one of the hotter months," Isaac Smith, a meteorologist with the weather service, said. "On average, July is hotter than August. To see that August ended up beating July is pretty impressive."

The average high temperature in August was 110.7 degrees, which officials say is the warmest ever recorded.

The average temperature for June through August this year was 96.7 degrees, beating the previous 2013 and 2015 record of a 95.1-degree average for the hottest summer in Phoenix.

Including Saturday, the Phoenix area has experienced 52 total days of temperatures 110 degrees or higher — far exceeding the 2011 record of 33 days, according to Smith. 

This year has seen hotter temperatures since moisture has not worked its way into the state, Smith said. 

"The temperatures have been allowed to really go up pretty significantly compared to what we have seen in the past. And our overall weather pattern has been supportive as well for these hot temperatures," including the position of the monsoon high, Smith said. 

Average temperatures have also been rising with human-caused climate change, and this summer has brought record heat in places across the Southwest. 

In Phoenix, the urban heat-island effect contributes to hotter temperatures. 

The vast areas of concrete and asphalt soak up heat from the sun during the day and radiate it at night, pushing temperatures higher than in other undeveloped areas. 

National Weather Service data for Phoenix shows that during the summer months from June through August, the average temperature during the 2010s was 3.1 degrees hotter than during the 1970s.

Moving forward, Phoenix can expect to see some above-normal temperatures throughout September. Labor Day weekend kicked off the month with an excessive heat warning through 8 p.m. on Monday. Phoenix and portions of south-central Arizona could see temperatures from 106 to 116 degrees and dangerously hot conditions.

After Monday, temperatures in Phoenix will start to drop to below 100 degrees by mid-week before warming up again by the end of the week, Smith said. 

The hottest Labor Day weekend on record also prompted the Salvation Army to open heat relief stations across metro Phoenix to combat the high temperatures, according to the Associated Press. 

Over the past 30 years, heat has been the cause of more deaths on average than any other natural disaster in the U.S., according to the National Weather Service. 

This year, 55 heat-related deaths have occurred in Maricopa County and 266 are under investigation, according to the Maricopa County Public Health Department data. 

The county saw 197 heat-related deaths in 2019. 

Reach the reporter at Audrey.Jensen@arizonarepublic.com or on Twitter at @Audreyj101.