PORTLAND, Ore. -

The National Weather Service is warning of critical wildfire conditions in Oregon and southwest Washington.

The agency issued a "red flag warning" through Tuesday after hot weather increased the risk of thunderstorms. Forecasters say there could be several rounds of thunderstorms Monday night.

Crews are already fighting dozens of fires in the Northwest. The weather service says that given dry conditions on the ground there's a "high potential for lightning strikes to generate several new fires."

A fire weather watch was also issued for parts of Washington state, with thunderstorms expected to develop along the crest of the Cascade Mountains and then spread north and west.