There was a piece in the Hartford Courant (hat tip to Karl) about how frozen the Connecticut River has been, that substantiates my piece about the river being frozen.
The 65-passenger boat sits at Eagle Landing State Park in the shadow of the East Haddam swing bridge, surrounded by ice that is 20 inches thick in places — a rare winter sight, especially along the lower Connecticut River. “For many years we were doing this [and] there was absolutely no ice,” he said. “Last year [the river] froze, but not this hard. The ice has forced Yuknat to cancel his popular bald eagle cruises for all of February, and he doesn’t expect to depart the dock until mid- to late March — if at all.
This place, the East Haddam swing bridge, will be a reference point next year. If my hypothesis is correct, then next winter, even if the temperature normalizes to historic means, there will be ice at East Haddam next year as well.