With heavy rain expected to drench the region tonight and tomorrow, the National Weather Service has issued a flood warning for the Assabet and Shawsheen rivers.
Forecasters say levels at the Shawsheen River, near Wilmington, will rise above flood level by late tomorrow morning and reach 8.6 feet by Tuesday morning. Flood stage is 7 feet.
The National Weather Service said if the Shawsheen water level reaches 9 feet, some roads along the river between Wilmington and Lawrence could become impassable, including Route 114, near Interstate 495.
The service said roadways in Maynard, Concord, and Hudson could be adversely affected if the Assabet floods.
After balmy weather across the state today, as much as two inches of rain could fall by the time the storm ends tomorrow.