The intense and fast-moving fires that have cut a path of destruction through the suburbs of Los Angeles, killing at least two people, are being driven by the region's powerful Santa Ana winds, with gusts that in some cases surpass hurricane-strength.

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.