The last few months have produced a stretch of the worst air quality on record, according to the Air Pollution Control District.
Satellite images show smoke gently blowing from several California fires out to the Pacific Ocean, a weather pattern keeping the Valley's air relatively clean for several days now.
"Right now we're seeing the smoke aloft," said Maricela Velasquez of the San Joaquin Valley Air Pollution Control District. "It's above us. But as the week goes through, we'll continue to see that smoke come onto the Valley floor."
Here's how: When you have a fire in the Central Valley -- which is essentially just a bowl -- the smoke can usually get out and air quality won't be bad everywhere. But when a high pressure system comes in, it essentially puts a lid on the bowl and the smoke has nowhere to go so it just collects on the Valley floor.
"The blocking high, basically, once it sits over a certain spot it likes to stay there for quite a while," said meteorologist Carlos Molina of the National Weather Service in Hanford.
Forecasters at the NWS say the lid will sit on our bowl for at least a week.
Air Quality Science Director Jon Klassen of the Valley Air District said, "We're expecting that to continue in the coming days."
By that time, our air will have collected smoke from the Creek Fire, the SQF Complex Fire, and even more recent fires to our west, like the Glass Fire in the Bay Area.
"Once the high pressure ridge kind of shifts more inland, it's going to start allowing that air flow to start reversing back over to west to east," Molina said. "What's going to happen is -- of course everything is blowing over the ocean (now) -- it's going to start later this week start shifting into the Valley."
The bottom line for everyone in the Central Valley will be a threat to health.
Throat irritation, burning eyes, and headaches are some of the more minor problems, but the smoke can cause problems with your lungs and heart.
Even before wildfire smoke started to pour into the valley, the American Lung Association ranked Valley cities among the worst in the country for year-round particle pollution. Bakersfield was number one, followed by Fresno-Madera- Hanford collectively. Visalia was next and then the Los Angeles-Long Beach area.
"PM 2.5, which is what's in smoke, actually can go into your bloodstream and so that's when you can start to have impacts on your heart," said Velasquez of the Valley Air District.
The cloth masks most people are wearing to reduce the spread of coronavirus won't protect you, and the N95 masks that will are in short supply.
People were reminded to limit their time spent outdoors as a return to unhealthy air conditions was expected this week. The fine particles can cause breathing and other health issues.
The Valley Air District recommends people track air quality on their website or at airnow.gov and stay indoors when it gets bad.