Cold Weather Events

When discussing extreme cold weather events, humidity shifts from being a "discomfort factor" to a primary driver of atmospheric energy and hazardous conditions. While arctic air is naturally dry, the interaction between this frigid air and moisture sources is what transforms a simple cold snap into a life-threatening winter storm.

In the context of weather prediction, moisture is the "fuel" for extreme events. Meteorologists look for the interaction between a cold air mass, like an Arctic Blast or the Polar Vortex, and a plume of warm, humid air—often from the Gulf of Mexico or the Atlantic. When these two collide, the humid air is forced upward over the denser cold air, a process that creates the massive clouds and heavy precipitation seen in blizzards and Nor'easters. Humidity also dictates the type of precipitation; for example, a layer of high humidity in a warm "nose" of air sandwiched between freezing layers is the classic recipe for an ice storm. Without this specific vertical moisture profile, an extreme cold event would remain a "dry cold" with clear skies, rather than a catastrophic freezing rain event that downs power lines and trees.

From a human safety perspective, extreme cold combined with humidity poses unique physiological risks compared to dry arctic conditions. In a dry "arctic" cold, the air acts as a poor conductor of heat, allowing well-insulated layers of clothing to work efficiently. However, when the air is damp or has a relative humidity near 100%, moisture can condense on the skin or infiltrate clothing fibers. This liquid moisture is a much more efficient conductor than air, "wicking" heat away from the body at a significantly faster rate. This phenomenon often makes milder temperatures (near 32 degrees F or 0 degrees C) feel more "biting" than deeper, drier freezes. Furthermore, high humidity in cold environments can exacerbate respiratory issues and increase the risk of hypothermia by making it nearly impossible for a person to stay truly dry, even without direct snowfall.