A disturbance will move up from the south beginning Christmas Eve, so morning sun will fade behind increasing clouds. Santa will need the help of Rudolph overnight, as light snow will break out across the area.
The light snow will continue into Christmas morning, but will mix with rain in Southeastern Massachusetts as temperatures warm.
Because of that, 0-1″ will fall from Boston down through Hingham and the South Shore. South of Plymouth, expect just rain from start to finish with this system.
North and west of Boston, where the precipitation stays as snow, expect 1-2″.
Partial clearing will take place by afternoon on Christmas.