One or two tornadoes are reported in New Hampshire a year. Most of these and small and only cause localized damage. The state is generally not associated with the huge tornados that occur in the Midwest and South. But, on July 24, 2008, a large thunderstorm system spawned a tornado that touched down in Epsom and Northwood just before noon. This EF-2 tornado, with winds up to 157 mph, tore through the middle of the state, and headed northeast to Ossipee. It killed one person, destroyed or damaged 60 structures and damaged thousands of acres of forest. It was the worst tornado in New Hampshire history and resulted in a Presidential Disaster Declaration for the affected counties.
Previously, the most significant tornado to strike New Hampshire occurred in September 1821. That tornado had a path half a mile wide, killed six, injured hundreds and left thousands homeless.
The southwestern portion of the state is considered a special wind hazard area as demonstrated by the high proportion of tornadoes and severe wind events that are experienced there annually. On July 3, 1997 several tornadoes struck this section of the state. An EF-1 tornado caused severe tree loss in Swanzey, destroying a building and damaged the stables at the Cheshire Fairgrounds. At the same time an EF-2 tornado struck Greenfield, causing damage to a summer camp, the recycling center and completely destroying a lumber facility. No deaths resulted from these events.
A microburst is a severe localized wind blasting down from a thunderstorm. These "straight line" winds are distinguishable from a tornado's circular pattern of destruction and debris.
Depending on the size and location of these events, the destruction to property may be devastating. Microbursts have produced winds as strong as 175 mph. Winds of this intensity can cause severe damage to forests and structures, and are certainly life threatening.
Microbursts have severely damaged several areas of New Hampshire. On August 18, 1991, five people were killed and 11 injured in Stratham. This downburst also caused almost $2.5 million in damage. In 1994, a microburst left a path one-half mile wide and 4-6 miles long in the town of Moultonborough. On July 6, 1999, two people were killed when a microburst struck central New Hampshire.