This region of New York State can see wildfire at any time of the year, but typically has two primary fire seasons. The spring fire season starts with the snowmelt in the southern part of the region, and progresses steadily north and west into the higher elevations, which hold snow for a longer period of time. Leaves on the trees have not come out, which allows a fairly strong spring sun to penetrate directly to the forest floor, rapidly drying out fine fuels (leaves, needles, twigs). In addition, there are generally several dry weather patterns that move through the area at this time with very dry air, and some wind. These are ideal conditions for a rapidly moving surface wildfire. It can start as early as mid March in Westchester, Putnam, and Rockland counties, and runs through mid May in the higher elevations of Ulster and Sullivan. It typically ends with full leaf out.
The second primary season is the summer fire season. After leaf out the relative humidity of the air mass tends to rise, making fine fuels less receptive to ignition. Occasionally, prolonged periods of little to no rainfall slowly dry out the forest floor. When a dry air mass moves in, conditions become ideal again for wildfire. During the summer however, the fire will penetrate into the half decomposed organic material in the ground and cause hard to extinguish “ground fire”. This season is driven primarily by weather patterns, but typically can occur in short bouts in the months of July, August, and September.
Fall wildfire seasons are more rare, and usually are an extension of a summer drought condition. Dried leaves from the drought fall off the trees in the fall and add a highly flammable fuel load to the existing fuel on the ground. Wind in November also contributes to this season.
Winter is the slowest season for wildfire, but fires can occur in the absence of snow cover and a relatively dry cold air mass.
Areas of historic large wildfires in this region include the Hudson Highlands, the Shawangunk Ridge, and the Eastern slopes of the Catskill Mountains.