The weather observed at MADISON, WI (KMSN) at 04:53 AM CST was: The skies were clear. Temperature: 0F (-18C) Dewpoint: -6F (-21C) Relative Humidity: 77% Winds were calm. Pressure: 1031.0 millibars. Altimeter:30.38 inches of mercury. The prevailing visibility was 10 miles.