Usually we begin to see the first flocks of northward-headed blackbirds in New England around Feb 15, but in recent years their arrivals are later and later. This year, the first wave arrived here yesterday.
"Blackbird" isn't a species - it's a category. Around here, it is mainly Red Wing Blackbirds and Common Grackle, who have spent their winter in the southern US and are headed for the marshy breeding grounds in the northern US and Canada. Very early migrators, they don't seem to mind nasty weather as long as it does not persist. (In the midwest and west, there are other species of Blackbirds.)
Photo below of male Red Wings. The females are an inconspicuous brown. In spring, the males get up on a branch, flash their red epaulets, and crow, in their territorial ritual, while the drab females skulk around and build nests in the rushes.