Last month’s extreme heat waves in Fresno set a new record for the hottest average temperature at 90 degrees — 1.3 degrees above the record set in 2021.

The average temperature is the midpoint between the high and low temperatures.

By contrast, the historical mean for average temperatures for July in Fresno is 82.4 degrees.

Nineteen days — more than half of the month — of temperatures at 105 degrees and above were “really impressive” but made that new record not entirely surprising, said meteorologist Andy Bollenbacher with the National Weather Service in Hanford.

Last year the ground was still moist from the winter’s rains, which helped to mitigate the summer heat. But the ground is drier this summer and consequently retained heat from the high-pressure ridge that was parked over the Valley for much of the month, he said.

The intensity and longevity of the heat waves that baked Fresno raised not only the daytime highs but also the nighttime lows, Bollenbacher said.

High Overnight Temperatures Are Dangerous

And the higher the lows, the more dangerous it is for people without access to air conditioning, because the constant exposure to heat puts more stress on the human body, he said.

In July there were also 19 days when the overnight low was 75 degrees or warmer, peaking at 84 degrees on July 13.

The National Weather Service considers overnight lows when issuing heat advisories because “those warm overnight lows can actually be extremely dangerous,” Bollenbacher said.

Depending on how August turns out, this summer of June-August could be one of Fresno’s hottest ever. June’s average temperature of 82.4 degrees was the fourth-hottest ever. The all-time record of 82.8 degrees was set in 1981.

August already is shaping up to be a hot month, although so far the extreme heat with highs at 110 or above that hit in July isn’t on the horizon, at least for the next week.

The forecast highs for Fresno are 104 for Thursday, 101 Friday, 105 Saturday, 106 Sunday, 105 Monday, 106 Tuesday and Wednesday, and 105 on Aug. 9, Bollenbacher said.

Friday could see some moisture and cloud cover that will lower the temperature by a few degrees, but the high is still forecast for triple-digits, he said.

Death Valley July Average? 108.5 Degrees

As hot as Fresno was in July, it was cool compared to Death Valley, which had an average temperature of 108.5 degrees.

That’s the highest monthly temperature ever recorded among the thousands of weather stations around the world, according to climatologist Brian Brettschneider.

🔥🔥🔥Death Valley, California, just set the record for the warmest month ever recorded on Earth. Their average temperature was 108.5F (42.5C). Their previous record, also the previous world record, was 108.1F (42.3C) set in July 2018. pic.twitter.com/TwKcVhqCrX

— Brian Brettschneider (@Climatologist49) August 1, 2024