Wildfires in Northern California have been in the headlines for weeks now, and our hearts go out to the victims who have lost their lives and their homes as well as the thousands who have been displaced.
“Fire Weather” is a term used to describe weather conditions that are conducive to fires.  But large wildfires are also also create their own weather, producing intense heat that causes localized winds that further intensify the conflagration.  Now, midway through the third year in a row when wildfires have dominated the news in Northern California, it’s become obvious that fires also affect the weather miles away from where they are burning.  Although it’s not the actual fire.  It’s the smoke.
One of the things that makes the Central Valley an ideal place for farming is the near-constant sunshine that dominates our weather from May through September.  Smoke from wildfires blocks the sunlight — how much depends on how smokey it is.
Low level smoke actually blocks out enough sun to create a false twilight that can last for days.  Two years ago when we had a large fire just a few miles west of the farm, we experienced almost a week of it.  The air was thick with smoke and you couldn’t even see across our fields.  Areas in the Sacramento Valley outside the smoke plume during that time experienced record high temperatures in the “hundred-teens” that week, but under the smoke cloud it barely broke a hundred and even then for just a few hours a day.
This climate-modification was a blessing and a curse.  In the short-term, it kept many of our crops from getting cooked as often happens when temperatures soar over 105 or so.  But in the longer-term, the lack of sunlight actually caused many of our summer crops to stop growing and ripening.  They were fooled into “thinking” that summer was over and fall had arrived.
So far in 2018, we haven’t experienced the type of extremely smoky conditions we did back in 2016.  But we have had numerous days of “marine layer” type conditions — high smoke that blocks the sun and creates hazy, humid and overcast conditions.  Without direct sun beating down on us, it is much less hot here.  The forecast yesterday was 102 but the high temperature was only 98.  It actually makes for more pleasant working conditions.
Right now, the fires in Shasta, Mendocino and Yosemite are essentially filling much of the Central Valley with smoke.  With new fires seemingly starting every few days and the end of fire season still months away, this could be our “new normal” for the rest of the summer.
I don’t want to make it sound like there’s anything good about massive wildfires burning out of control for most of the year.  Quite the contrary. And if 2016-2018 is the new normal, we are entering a time when fire may be regularly or even constantly playing an important role in the climate of our state.  It’s just another element in the complex feedback loop of climate change that will could make it harder for humans to grow food in the future.