From the National Weather Service:
URGENT - WEATHER MESSAGE National Weather Service Boston/Norton MA 347 AM EDT Tue Aug 14 2018 MAZ015-016-019>024-141300- /O.NEW.KBOX.FG.Y.0029.180814T1000Z-180814T1300Z/ Suffolk MA-Eastern Norfolk MA-Eastern Plymouth MA- Southern Bristol MA-Southern Plymouth MA-Barnstable MA-Dukes MA- Nantucket MA- Including the cities of Boston, Quincy, Plymouth, Fall River, New Bedford, Mattapoisett, Chatham, Falmouth, Provincetown, Vineyard Haven, and Nantucket 347 AM EDT Tue Aug 14 2018 ...DENSE FOG ADVISORY IN EFFECT UNTIL 9 AM EDT THIS MORNING... The National Weather Service in Boston/Norton has issued a Dense Fog Advisory, which is in effect until 9 AM EDT this morning. * VISIBILITIES...One quarter mile or less at times. * TIMING...Through mid-morning. * IMPACTS...Limited visibilities will make travel very difficult. * LOCATION...Massachusetts east coast from Boston southward and Massachusetts south coast, including Cape Cod and the Islands. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Dense Fog Advisory means visibilities will frequently be reduced to less than one quarter mile, for at least 3 hours. If driving, slow down, use your headlights, and leave plenty of distance ahead of you.