County officials are urging drivers not to drive past road closed signs.
The Nooksack River at North Cedarville crested early Thursday morning and is expected to fall back to action stage later in the night.
The NWS has issued a flash flood watch for the Skagit River Basin due to potential levee and dam failures.
The Division Street Bridge to and from West Mount Vernon is closing at 6 pm on Thursday.
All residents north of the Nooksack River in Everson are being advised to leave the area.
Several schools in Whatcom County have submitted a proposal to move larger 1A private schools up one classification.
Sumas residents can pick up sandbags at the City Shop on Kneuman Road until 7 pm on Wednesday.
The Nooksack River at Ferndale is expected to see the most flooding when it crests around 21 ft. on Thursday afternoon, which puts it just above the moderate flood stage.
Anyone in the impacted flood areas should secure their belongings and property, get a go bag ready and have an evacuation route planned.
Communities often impacted include Marblemount, Rockport, Concrete, Hamilton, Lyman and surrounding areas.