Upwards of 60 millimeters of rain is expected to fall in a matter of hours.
“In the afternoon and evening, there could fall 40 to 60 millimetres locally in the course of six hours. Follow the weather radar and updated information on varsom.no,” weather site YR wrote.
Officials have asked people to refrain from driving in nothern and inner Hordaland.
The extreme weather warning applies to Boknafjorden in the south to Sognefjorden in the north.
“Throughout the day we expect surface water, flooding and the risk of landslides and debris,” metoerologist Tone Kristin Taule told broadcaster NRK.