People in four states across the U.S. Southwest and California were warned of dangerous fire weather conditions on Monday, with dozens of counties under red flag warnings. The National Weather Service (NWS) cautions that a red flag warning indicates critical fire weather conditions are either underway or likely to develop shortly.

Here's what to know about firefighter efforts, FEMA grant funding, evacuation orders and weather conditions for the eastern Arizona wildfire.

According to the NWS, a red flag warning is issued when the combination of dry fuels and weather conditions support extreme fire danger. For northern Illinois and northwest Indiana, the red flag warning criteria includes sustained 20-foot winds of 20 mph or higher, relative humidity less than 25% and 10-hour fuel moisture at 8% per day.