Why is California’s wind blowing so hard in January?

In the hours before fierce Santa Ana winds rushed through the canyons of Los Angeles, igniting homes and claiming lives, we felt Diablo winds here.

But they just created ripples in mud puddles. They stirred the heavy leaves on soggy trees. They warmed our yards and sent fresh breezes through the air, slightly scented with the perfume of early manzanita and daffodil blossoms.

“The same weather system that generates Santa Ana winds also produces Diablo winds, often 12 to 24 hours earlier,”...