The official start of summer is more than two weeks away, but the extreme heat typical of a Valley summer will slam Fresno on Wednesday when the thermometer is expected to hit 105 degrees and climb to 107 degrees on Thursday and then 105 again on Friday, prompting the National Weather Service to issue an excessive heat warning for the week.
While not every triple digit temperature is the same, a lot of factors are considered before excessive heat warnings are issued, according to Victor Proton, senior meteorologist for the weather service office in Hanford.
“A 100-degree at the end of July is not the same as 100-degree day in April and the impacts of the body because the body has to adjust,” said Proton. “We look at more than just the high temperatures. We look at the low temperatures, humidity and a lot of other factors that goes with it to determine when we issue an excessive heat warning.”
In 2021, Fresno recorded a record 65 days of triple digits. That was shattered by last year’s 69 days. The hottest day ever recorded in Fresno is 115, which occurred on July 8, 1905. A 114-degree day on Sept. 6, 2022, tied for the second-highest.
The weather service extended an excessive heat warning for the San Joaquín Valley, including Fresno, Madera and Merced counties starting at 11 a.m. Wednesday through 8 p.m. Friday when temperatures are expected to be between 103 to 108 degrees.
What is causing the heat
Proton said “this massive bubble of heat called upper-level ridge” of high pressure is causing the heat.
You can think of it as a big bubble that is building up that has been over central México for several weeks and is now expanding over Southern California, Central California and getting up to almost Oregon, coming faster and a few weeks earlier than it normally does, Proton said.
The probabilities of the high temperature being 105 Deg F or hotter for select locations this week. #cawx pic.twitter.com/SErD0BV3w3
— NWS Hanford (@NWSHanford) June 4, 2024
“Typically, you see this until more towards the 4th of July with the large ridges,” Proton said.
Proton said the average high temperature in Fresno for this time of year is 87 degrees while normal are around 61 degrees.
“And we are looking at highs of 107, so that is 20 degrees about normal,” Proton said. “And we are looking at lows in the lows 70s.”
While it is normal to have 100-degree heat in June, Proton said this week’s temperatures are “a little bit unique” because they start pushing to the 110-degree mark in some areas.
“A 10-degree jump makes this so much more significant than just the 100-degree day. Going the extra 10 degrees really has some strong impacts,” said Proton.
The official average temperature for Fresno is taken at Fresno Yosemite International Airport, with the current forecast for Thursday’s high at 107, but five miles west near Fresno City Hall you can expect temperatures around 110 or 111 because of all the heat island effect, said Proton.
“People that live more in the cities end up being impacted more by heat, especially overnight when they can’t cool it down,” he said.
Proton said on Thursday for example, the 121-year-old record high of 107 at the Fresno airport could be in jeopardy.
“And the record warmest minimum temperature is 75, which was set in 1926. That also is in jeopardy, so it gives you an idea of the significance of this event of why we’re looking at it as being an excessive heat event,” he said.
Proton said the average temperature for Thursday is approaching the upper 90s for the day.
“You are looking at prolonged periods without any relief,” Proton said. “So you have Wednesday, Thursday, Friday, even Saturday and Sunday, our maximum temperatures cool down 10 degrees, but even that is still 97, 98, 99 degrees which is 10 to 12 degrees above normal for the time of the year.”
How to stay cool
The city of Fresno announced Monday that the city’s cooling centers will be open as the weather service projected temperatures to rise to 105 degrees or above in Fresno on June 5 and June 6.
The FAX bus system will provide free transportation along normal routes to three sites designated as cooling centers whenever the temperature gets above 105 degrees.
Doors to the Maxie L. Parks Community Center, 1802 E. California Ave.; the Ted C. Wills Community Center, 770 N. San Pablo; and, the Mosqueda Community Center, 4670 E. Butler will open from 12 p.m. to 8 p.m. those days.
The state has also entered phase 2 of its extreme temperature response plan.
A list of local cooling centers operated by county can be found here.
Details on heat illness prevention requirements and training materials are available online at 99calor.org. Cal/OSHA’s heat illness prevention standard applies to all outdoor worksites.
The California Department of Public Health (CDPH) has created a Heat & Summer Safety toolkit to provide resources and communication tools that can be shared, including the difference between heat exhaustion and heat stroke.
How to avoid problems with the heat
Stay cool during the hottest time of the day
Stay hydrated: drink plenty of fluids, especially water, avoid sugary, alcoholic drinks
Stay connected by monitoring those at high risk of heat-related illness including infants, young children, people 65 and older, and individuals with chronic illnesses or disabilities.
Stay informed by checking the local news for weather forecast, extreme heat alerts and cooling centers.
