This story has been updated.

A fire alongside Interstate 5 north of Cottage Grove closed on- and off-ramps near milepost 177.

As of about 3 p.m. Thursday, Aug. 21, the Oregon Department of Transportation was telling drivers to expect a delay of less than 20 minutes in the area.

South Lane Fire & Rescue responded to the blaze, which was reportedly about 5 acres.

The National Weather Service had issued a red flag fire warning for the southern Willamette Valley, including Eugene and Springfield, from Thursday afternoon through the evening.

A weather system brought strong winds, low humidity and high temperatures — textbook conditions for fast-spreading, extreme fires.

The warning covered an area in drought, where a rainy winter fueled the growth of tall, dense grass and shrubs that have since dried out. Recent rain wasn’t enough to offset the conditions, and low humidity continues to strip away remaining moisture.

Under these conditions, even routine activities carry risk.