Historic heat wave expands across California, wildfire risk builds

The record-breaking heat wave roasting the West is expanding its grip on Thursday, with the focus of the triple-digit heat shifting into California — particularly the Central Valley and desert regions.

Why it matters: Across the West, the combination of record heat, preexisting drought conditions, and dry lightning strikes from afternoon thunderstorms threatens to ignite numerous wildfires Thursday.

Fires have already been burning in Montana, Arizona and other states affected by the heat wave.

More than 40 million people across the West and Southwest are likely to see temperatures in their area exceed 100°F during the next several days.