From the National Weather Service:
Special Weather Statement National Weather Service Boston/Norton MA 736 PM EDT Thu May 17 2018 MAZ019>024-RIZ006>008-180300- Eastern Plymouth MA-Southern Bristol MA-Southern Plymouth MA- Barnstable MA-Dukes MA-Nantucket MA-Washington RI-Newport RI- Block Island RI- Including the cities of Plymouth, Fall River, New Bedford, Mattapoisett, Chatham, Falmouth, Provincetown, Vineyard Haven, Nantucket, Narragansett, Westerly, Newport, and New Shoreham 736 PM EDT Thu May 17 2018 ...BRIEF PERIOD OF DENSE FOG THIS EVENING TOWARDS MIDNIGHT... Patchy fog, locally dense in spots has either developed or is expected to develop this evening and overnight towards midnight. Areas along the immediate south coast of New England are likely to be impacted especially with visibility down as low as half a mile. Areas of poor visibility will improve after midnight as light winds shift and increase out of the north ushering drier air across the region eroding any fog. Motorists should be prepared when encountering lower visibilities in spots associated with fog, allowing for increased braking distance between vehicles.