What is a red flag warning? What to know as Chicago area faces fire danger

The Chicago area is under a fire weather watch for Wednesday, but some parts of the region could be upgraded to a “red flag warning.”

According to the National Weather Service, the possibility of such an upgrade is highest along and north of Interstate 88, but the entire area is set to see enhanced fire risk conditions because of high temperatures, gusty winds and low relative humidity, according to officials.

But what exactly is a red flag warning?

Such a warning is issued when areas experience warm temperatures, extremely low humidity, and strong winds, all of which can combine to rapidly accelerate the spread of any fires that start, according to the NWS.

The Chicago area is expected to see all of those weather events on Wednesday, with highs soaring into the mid-to-upper 60s, relative humidity of 20% or even lower, and wind gusts that could exceed 40 miles per hour at times.

Those wind gusts are expected to be strongest in the northern parts of the Chicago area, but gusty winds and dry conditions are also expected along and north of Interstate 80, as well as in Cook County.

In both fire weather watches and red flag warnings, residents are urged not to start open fires outdoors, and to refrain from throwing cigarettes or matches out of a moving vehicle.

All fires must be extinguished properly, drowned with plenty of water and stirred to make sure it is cold to the touch, according to officials.

Winds will eventually calm heading into Thursday, but another weather threat is expected to develop on Thursday as showers and thunderstorms could occur in the area. Parts of the Chicago area, including LaSalle, Grundy, Will and Kankakee counties in Illinois, are at a marginal risk of severe storms on Thursday, with gusty winds and heavy rain possible.

Stay tuned to the NBC 5 Storm Team for all the latest weather news and information, and be sure to download the NBC Chicago app for real-time weather alerts sent directly to your phone.