Wildfire season severity is determined by a multitude of factors and weather is one of them. Last year we had a fall with plenty of rain which helped temper this summer’s fire season.
While this is loosely correlated, I do not do it lightly. I spoke with a meteorologist about this last year, and there is some science.
When a lot of rain falls in the fall, the dry earth soaks it up like a sponge cake, absorbing fruit juice. This moisture is stored in the ground and vegetation ahead of the winter snow. When it comes time for the snow to melt, the moisture is already in the soil and plants, slowing the snow melt and keeping humidity levels higher further into the spring and summer. Fire weather is impacted by fuel moisture and relative humidity. When these are higher, things just are not as flammable.
In 2021, California and western Nevada had some serious wildfires, including one of the largest single fires in recorded California history. In the fall of 2020, there was an early snow event that essentially sealed the dry and parched ground over with a thick layer of snow. Along with a warmer than average spring, the west was essentially drier than normal and poised to burn.
In the fall of 2021, the atmospheric river that washed across the west dropped inches of rain across the foothills and higher elevations. Eventually, this rain turned to snow but not before rain trickled into the earth. The summer of 2022 saw relatively few devastating wildfires.
This is part conjecture and part science, but something I have been thinking and writing about for a while. This idea of connecting fall rain to the following summer wildfires is a topic I will continue to explore. There is an important connection.
As September shifts into October and fall colors engulf the mountains, the forecast looks to be dry. However, September was an unusually wet month for parts of the west and perhaps this moisture will stick around next spring and summer to keep fuels moist and humidity levels elevated.