By John Dodge

CHICAGO (CBS) — Residents in much of Chicagoland typically ride out a tornado warning for anywhere from 45 to 60 minutes, according to data from the National Weather Service.

That’s the average time for a tornado warning for Cook County and Lake County in Northwest Indiana.

The NWS examined data for the past 20 years, from 1994-2013.

The average tornado warning time was lower in Lake County, Ill. (15-20 minutes) and DuPage (20-25 minutes).

Farther to the south in Will County, the average time rose to 75-90 minutes.

Tornado warning times were typically lower in counties to the west and north of the Chicago area.

Counties to the far southwest of Chicago were much higher.

Three counties studied–Livingston, LaSalle and Iroquois–had the highest warning times, ranging from 90 minutes to two hours on average.

Farther to the east in Indiana, times dropped to about 30 minutes.

The area-wide average was just under one hour, NWS found.

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