From October to March, high pressure systems can build over the Great Basin, an arid plateau located mainly in Nevada and Utah, causing winds to blow from the east and northeast. As the air descends off the desert plateau, it warms and funnels through the Santa Ana Canyon into the Los Angeles Basin and San Fernando Valley at high speeds. The Santa Ana winds can carry large amounts of dust and sand, which can cause poor air quality in highly populated areas. The combination of the heat and strong winds can dry out vegetation. During the fall, the Santa Anas are typically responsible for spreading brush fires that have started in the area, due to months of little or no rainfall. The Santa Ana Winds have also been called ‘devil’s breath.’
Source: NWS, ESRI, USGS | LA Times