Dense fog has blanketed parts of Massachusetts, causing limited visibility during the morning commute.
Visibility at Logan Airport is down to just a quarter mile, said meteorologist Benjamin Sipprell. Several other areas were reporting thick fog, including Waltham.
Southerly winds are driving moisture northward over cooler ground, causing the fog, he said.
The ground temperature dropped after last month’s series of cold weather and today’s warm, moist air is mixing with the cooler surface, producing fog.
“November was a very cold month comparatively to the last 14 to 15 months here that we’ve been posting above normal temperatures,” Sipprell said. “The fog right now is mainly across the Cape and Martha’s Vineyard, approaching up across the southeastern coastal plain and into Boston.”
The southerly flow of air will likely continue throughout the day, he said.
“Unless the sun can really get out and peek through, this can last into the midday hours,” Sipprell said. “It is possible to see this fog level stay with us through the evening hours.”
Foggy conditions are improving across the Cape and Islands, but drivers in Boston will have to wait for the visibility to improve in the city.
Visibility in Nantucket has improved to seven miles, he said.
“Warm air will intrude across the region causing conditions to mix out and the fog to dissipate,” Sipprell said. “But with boston so far north, it could take some time.”
Temperatures today will climb as high as 58 in Boston.
Morning commuters won’t have to fight through thick fog Wednesday morning, but drivers will still need to be cautious, because rain is expected.
Showers will build across Greater Boston starting around midnight tonight, Sipprell said.
The rain will continue into Wednesday, but the front should move through Boston during the morning hours and the wet weather will clear by midday, he said.
Sipprell said it will be nothing more than “a simple benign rain,” and that Bay Staters should enjoy today’s warm temperatures because the rest of the week will be cooler.
Wednesday’s temperatures will be in the mid-50s and the rest of the week will be in the 40s, according to the National Weather Service.
Melissa Werthmann can be reached at email@example.com.