Cold fronts
The passage of weather fronts greatly affects wind, causing changes in wind direction, wind gusts and increased wind speed. With the passage of a cold front, winds shift 180 degrees from south to north in a clockwise direction. The speed of the shift depends on how fast the front is moving. A backing fire can suddenly change to a head fire. Remember too, that relative humidity will drop behind the cold front. If a cold front is coming through, give serious thought to postponing a prescribed burn.
Pay attention to high and low pressure systems prior to, during and after your burn. Wind directions will shift as pressure systems pass.
Courtesy of NWCG, S290
Winds, temperatures and relative humidity associated to a front will vary as a front passes
Courtesy of NWCG, S290