The 'Siberian Express' Tightens Its Grip

A tourist bundles up to brave frigid February temperatures.

You may have noticed it's pretty cold outside (to say the least)! Temperatures are way below normal, and will stay that way all week. Steven DiMartino, a meteorologist for the New York City and Philadelphia metropolitan areas, explains what's causing the prolonged cold snap, including what the "Siberian Express" weather system has to do with it.