The winds are common in California in the colder months, but they can sometimes help spread dangerous wildfires.

Multiple wildfires are currently raging through Los Angeles County, forcing evacuations and destroying neighborhoods. A long dry summer created ample fuel that has combined with a lack of rainfall over the winter to extend fire season conditions.

By the time the winds get to the point where the Eaton Fire broke out in Altadena on Jan. 7, it’s not uncommon for them to have less than 5 percent relative humidity, meaning essentially no moisture at all.