The triple digit temperatures are having a major impact on the spread of West Nile Virus here in the valley.
Experts say the heat speeds up a mosquito's life cycle and that means more breeding.
It also accelerates the West Nile Virus replication process.
Mark Berman and his family are visiting the valley from the Netherlands.
He knew nothing about a recent collection of mosquitoes that were infected with the disease.
Tourist Mark Berman says, "We are going to spray absolutely, don't plan to get bitten or ill."
The mosquitos were discovered in the Sherwood area, near Sanger in eastern Fresno County.