A cold weather front is defined as the changeover region where a cold air mass is replacing a warmer air mass. Cold weather fronts usually move from northwest to southeast. A warm weather front is defined as the changeover region where a warm air mass is replacing a cold air mass.
A warm weather font is defined as the changeover region where a warm air mass is replacing a cold air mass. If colder air is replacing warmer air, it is a cold front, if warmer air is replacing cold air, then it is a warm front
