photo credit: Greta Mart/KRCB
A smoky haze hangs low, over 101 in Petaluma

If you've looked up, or breathed in today, you've noticed smoke and haze. Though local fire departments have been on alert, major active wildfires are quite distant. The bad air quality is mainly caused by shifting atmospheric conditions.

Though tens of thousands of acres are alight across the west, the north bay has been mostly spared from heavy smoke. Until this week.

"There are several fires across Northern California and Southern Oregon and we've gotten into this pattern where it's bringing the winds out of the north, heading towards the south, so those winds are picking up the smoke from the fires and bringing it right down towards Sonoma County and the North Bay there," said Brian Garcia, a meteorologist with the National Weather Service in Monterey.

Garcia said there's nothing unusual about this change. It's seasonal.

"Typically, what we would see is that the wind going from the ocean onto land, but as we get into late August, into September and really late September into October, we start to get these periods where we actually get winds out of the north or even the northeast. So, any sort of fires that exist, if the flow is right, we can tap into those conditions, those smoky conditions and drag them right across our area," he said.

As to how long we'll have to endure poor air quality?

"Tomorrow, we'll continue to see some smoke. Will it be as thick as today? It might start somewhat as thick, but as we start to turn those winds, from coming out of the north to more of a coming out of the west, we'll start to slowly clear out, through the day, but with that little bit of a ridge of high pressure trying to hold on overnight, it could lock some smoke down in some of the valleys tonight, and it will take the winds starting to really kick in tomorrow afternoon before it really scours it out," Garcia added.

Another aspect of that seasonal change is right around the corner. Low pressure out of the north arriving Friday will bring dramatically cooler temperatures, cutting afternoon highs as much as 20 degrees.