Powerful, hot and dry winds like those that have fanned the deadly wildfires now raging in California are a common occurrence in the state, a result of regional atmospheric patterns that develop in the fall.

The impact of climate change on the winds is uncertain, although some scientists think that global warming may at least be making the winds drier. “That is a pretty key parameter for fire risk,” said Alex Hall, a climate researcher at the University of California, Los Angeles.

The winds, known as Diablo winds in Northern California and Santa Ana winds further south, have their origin in the high desert of the Great Basin of Nevada and parts of Utah. High-pressure air that builds over that region flows toward lower-pressure air over California and the coast.