From the National Weather Service:
URGENT - WEATHER MESSAGE National Weather Service Boston/Norton MA 716 PM EDT Sat Apr 13 2019 ...DENSE FOG ADVISORY IN EFFECT UNTIL 7 AM EDT SUNDAY... The National Weather Service in Boston/Norton has issued a Dense Fog Advisory, which is in effect until 7 AM EDT Sunday. * VISIBILITIES...One quarter mile or less at times. * TIMING...From this evening through 7 AM Sunday morning. * IMPACTS...Limited visibilities will make travel very difficult. * LOCATION...Coastal Rhode Island and south coastal Massachusetts, 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.