What is a ‘fire weather watch'? What the weather alert means for Chicago

Dry, gusty conditions in Northeastern Illinois led the National Weather Service to issue a fire weather watch for the entire Chicago area Monday.

The fire weather watch for Chicago comes alongside a wind advisory for much of the region, with gusts as high as 50 miles-per-hour at times, the NWS said.

Such strong winds are expected to continue Monday afternoon and into the evening, not letting up until the overnight hours, NBC 5 Meteorologist Alicia Roman said.

But what exactly does is fire weather watch, and what does it mean? Here's a break down.

Fire weather watch for Chicago

The fire weather watch was set to go into effect Monday for all Chicago area counties, as well as Lake County in Indiana. The watch was initially issued due to the combination of "strong winds, dry air and dry fuels," the NWS said. Such watches are typically issued over the summer months, Roman noted.

"Any grass or brush fires that ignite may have the potential to quickly spread out of control," the NWS said. "Use extreme caution when disposing of smoking materials."

By Monday afternoon, the NWS said there were "elevated fire concerns" for Kendall, LaSalle, Grundy and Will Counties.

What is a fire weather watch and why was it issued?

According to the NWS, a fire weather watch is issued "when the combination of dry fuels and weather conditions support extreme fire danger."

Different parts of the country may have different criteria for fire weather watches, the NWS said.

"In Northern Illinois, and Northwest Indiana, the conditions include sustained 20 ft. winds of 20 mph or higher, afternoon relative humidity less than 25% and 10-hour fuel moisture at 8% or less for one day," the NWS said.

Temperatures in the low-to-mid 40s Monday and dewpoints in the upper single digits and low teens will yield minimum relatively humidity values around 25%, the NWS said,

"It's possible that dewpoints mix down even lower than forecast which would further lower relative humidity," the NWS said. If this does occur, the NWS could "upgrade" the fire weather watch to a red flag warning, officials said.

According to officials, fire weather watches are issued 72 hours before such conditions are expected to occur. Alternatively, a red flag warning is issued when the conditions are expected to occur or occurring within the next 24 hours, the NWS said.

Monday, both the strongest winds and the driest air are expected near and south of I-88, the NWS said.

Wind advisory issued

A wind advisory was also issued, the NWS said, for Cook, DuPage, DeKalb, Kane, Lake and McHenry counties in Illinois, and Kenosha county in Wisconsin. The advisory takes effect at 9 a.m. Monday, lasting through 6 p.m., the NWS added.

According to the NWS, winds could gust as high as 50 mph, especially in areas to the north and west. Southwest winds of 20 to 30 mph could be expected, with frequent gusts up to 45 mph.

"Gusty winds will blow around unsecured objects," the NWS warned. "Winds this strong can make driving difficult to hazardous, especially in high profile vehicles on north to south roadways. Small or dead tree limbs could be blown down and a few power outages may result."

Warmer temperatures

While Monday started out in the teens, temperatures will rise into the mid-40s by Monday afternoon, Roman said.

Mild temperatures in the 40s were expected to remain in the forecast through the week, Roman said, with temperatures near 50 degrees on Thursday.

"All that cold air we had last week has moved far away from us," Roman said.