Parts of San Joaquin County saw more than half an inch of rain last week and more rain on Sunday. Reports with warmer temperatures on the way that can mean a big jump in the mosquito population.
This year San Joaquin County reported five human cases of West Nile Virus, Sacramento County ten, and Stanislaus County 30 - with Sacramento, Sutter, and Stanislaus Counties having two deaths each from the disease.
The recent rains filled everything from flower pots to ditches with water in the Central Valley.
It only takes a couple of tablespoons of standing water for mosquitoes to breed.
Aaron Devencenzi with San Joaquin County Mosquito Control says normally the number of mosquitoes start to dwindle in September but the rain coupled with warmer weather could cause a resurgence.
"Typically we're seeing mosquitoes anywhere from, I would say, March to probably as long as the mid-part of November."
Devencenzi says West Nile Virus is still a threat.
"This year we're had a significant amount of West Nile Virus, probably close to the most we've ever seen within the population."
Devencenzi says people should try to eliminate all standing water around the house and use mosquito repellent when outdoors.