Weather Service calls a heat wave for Fresno. How hot will it be and how long will it last?

Fresno has already seen one record-setting heat wave this summer and is in store for a second — a brutal run of 100-degree-plus daily highs with lows above 80 degrees.

“Sadly, our next spell of triple digit heat looks like it could be our longest one yet this summer,” the National Weather Service wrote in its Fresno forecast discussion on Wednesday.

“Its lengthy duration will most certainly stress heat sensitive individuals and possibly livestock.”

An excessive heat watch has already been called for the Fresno area starting 1 p.m. Friday and will likely be raised to an excessive heat warning as the weekend progresses.

High temperatures of at least 105 are likely across the San Joaquin Valley early as Thursday, with temperatures rising through the weekend. The area will get a break — of sorts — by next Tuesday and Wednesday when the high temperatures will return to just five to eight degrees above normal.

Before then, though, we could have multiple days where the temperature is at or above 110 degrees. The Weather Service is predicting a high of 109 on Friday, 111 on Saturday and 112 on Sunday (when the chance of hitting 110 or more is at 50%; there is a 98% chance it will be hotter than 108).

The lows for those days are expected to be above 80 degrees, which could break high minimum daily temperature records.

Temperatures above 110 degrees are rare in Fresno and having multiple 110-degree days exceedingly so, according to Weather Service data. Since 1948, there have been less than a dozen instances of multiple 110-degree days and only one instance in which there was more than two in a year.

That was in 2006, when a July heat wave recorded temperatures above 113 for three days straight.

This story was originally published July 7, 2021 at 10:59 AM.