A wildfire in the hills near the U.S.-Mexico border exploded early Friday morning over thousands of acres, prompting evacuation orders throughout the Otay Wilderness Area and triggering school closures as well as likely power shutoffs for tens of thousands of people.

With parts of Los Angeles County still smoldering from wildfires, the expected rain this weekend would seem like a welcome relief. But how the rain falls could make the difference between a disaster respite or a disaster repeat.