Critical Fire Weather Patterns

As part of the Open Burning Weather Awareness Campaign from the National Weather Service in Burlington, we will examine a critical fire weather pattern that impacts the North Country during peak fire season.

The National Weather Service in Burlington, Vermont monitors weather patterns for situations that would have an impact on fuels and fire. One common pattern found during peak fire season has a high pressure system building down into the region from central Canada. This system will bring dry air into the area, lower relative humidity values, and help dry the dead fuels already on the ground. Clear skies typically accompany these systems and cause the fuels to dry even further. Gusty northwest winds can also be found in this scenario that can help a fire spread rapidly if one were to develop. The image below shows a favorable setup to bring the critical weather conditions described above into the region.

This is a favorable weather situation which can easily impact open burning. Setting fire to a debris or brush pile in these conditions could result in more intense burning since the fuels have become even drier. If gusty winds exist, burning embers could be transported further away from the debris or brush pile and start a new fire in any dry fuels laying on the ground. The wind would also help spread that new fire.

Over time, the high pressure system builds right over the area and can persist for a lengthy period of time. What this means is that we get an extended period of no precipitation, plenty of sunshine, warmer temperatures, and lower humidities. These conditions all help to dry the fuels. Most importantly, the winds are typically light in this scenario. So if you are trying to burn, it might look like there are no concerns, but now the fuels around you have become so dry that a fire could spread quickly despite the lack of wind.

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(All photos taken on Vermont fires in 2012 and are courtesy of Brooke Taber, NWS Burlington, Vermont)