Polar Vortex: During the winter months, the polar vortex, a large area of low pressure and cold air that circulates around the North Pole, can become displaced and extend its reach southward. This can bring extremely cold air masses into the New England region, resulting in frigid temperatures.

Jet Stream Shifts: The jet stream is a narrow, fast-moving air current in the atmosphere that influences weather patterns. Shifts in the jet stream's position can disrupt the normal flow of weather systems, allowing cold air from the Arctic to penetrate deeper into New England.

Snow Cover and Albedo Effect: Snow has a high albedo, which means it reflects a large portion of the sun's energy back into space. When there is extensive snow cover in New England, it can lead to a decrease in the amount of heat absorbed by the Earth's surface, resulting in colder temperatures.

Radiational Cooling: During clear nights, when there are few clouds to trap heat near the ground, radiational cooling occurs. The Earth's surface loses heat through longwave radiation, leading to a drop in temperatures and contributing to the overall cold conditions in New England.

Influence of Large Water Bodies: New England is located near the Atlantic Ocean, which can have an impact on winter temperatures. The ocean's temperature is relatively mild compared to the land during the winter months. This temperature differential can create cold air masses that move inland, exacerbating the cold conditions in the region.

The convergence of these factors, such as the polar vortex, jet stream shifts, snow cover, radiational cooling, and the influence of nearby water bodies, can contribute to the extremely cold temperatures experienced in New England during the winter months.