Fires and flooding on the West Coast, record cold and gusty winds on the East Coast. Brace yourself for Thanksgiving week, 2018.

Northern California could get as much as 7 inches (18 centimeters) of rain, according to forecasters. The good news is that the downpour could help tamp down a deadly fire that’s consumed more than 151,000 acres in the region, and help clear the smoke that’s been poisoning the air.

But there’s bad news, as well. The fire, which has killed at least 79, has left an oily residue behind that could combine with the rain to cause dangerous flooding, and send debris, ash and unstable dirt and rocks tumbling down hillsides cleared of vegetation.

The “burn scars are impermeable to water,” said David Roth, a senior branch forecaster at the U.S. Weather Prediction Center in College Park, Maryland, in a telephone interview “The more recent the fires the worse it is, but these burn scars linger for five years.”

While the rains fall on California, the Northeast will see temperatures drop as much as 35 degrees Fahrenheit below normal for the coldest Thanksgiving since 1996, Roth said.

Boston will likely set a record for both the day and the holiday with a high of just 21 degrees Fahrenheit (-6 Celsius). New York will reach 27 degrees, just short of a record for that city, and Washington should get to 35. Gusty, balloon-juggling winds, will make it feel even colder, Roth said.