© Jason Redmond / Reuters
The affected counties include: Benton, Clackamas, Clatsop, Columbia, Lane, Lincoln, Linn, Marion, Multnomah, Polk, Tillamook, Washington, and Yamhill.
The declaration allows the counties to apply for state funding to repair damage, in addition to providing them with emergency response personnel that can respond to communities if local resources are stretched too thin.
A series of powerful storms and record rainfall have slammed the state since Monday, causing widespread flooding that has closed roads from Portland to the coast. At least two storm-related deaths have been confirmed by officials.
"Heavy rains and wind have required the evacuation of residences, and mudslides and high water have severely damaged or blocked major roadways in these areas of the state," Governor Brown said in a statement. "The emergency declaration ensures state resources, emergency response personnel, and equipment can be activated to respond to communities in need if their local resources are exhausted."
The deluge set a daily record in Portland, which saw 2.75 inches of rain on Monday alone, CNN affiliate KOIN said.
The storms also brought lightning strikes, and an F1-rating twister that reached maximum wind speeds of 15 miles an hour.
The state of emergency will remain in effect until the governor's office lifts it.
Whatever happened to that massive Drought that they swore up and down would never end? They're still at it in California, whining and professing that no amount of rain will ever make up for the lean 4 years.
Brown in Oregon, meet Brown in California. Kate and Jerry are trying to out-Brown each other.