According to the United States Census Bureau, the town has a total area of 41.3 square miles, of which 39.4 square miles is land and 1.8 square miles is water. Wilmington is drained by the North Branch Deerfield River, as well as Meadow Brook, Rose Brook, Haystack Brook, Hall Brook, Ellis Brook, Beaver Brook, Negus Brook and Wilder Brook. It is located in the Deerfield Valley of the Green Mountains.
As of the census of 2000, there were 2,225 people, 992 households, and 597 families residing in the town. The population density was 56.4 people per square mile. There were 2,232 housing units at an average density of 56.6 per square mile. The racial makeup of the town was 97.80% White, 0.22% African American, 0.27% Native American, 0.58% Asian, 0.18% from other races, and 0.94% from two or more races. Hispanic or Latino of any race were 0.94% of the population. There were 992 households out of which 26.0% had children under the age of 18 living with them, 48.6% were married couples living together, 7.8% had a female householder with no husband present, and 39.8% were non-families. 32.5% of all households were made up of individuals and 8.0% had someone living alone who was 65 years of age or older. The average household size was 2.24 and the average family size was 2.84. In the town, the population was spread out with 21.6% under the age of 18, 7.0% from 18 to 24, 26.7% from 25 to 44, 30.6% from 45 to 64, and 14.1% who were 65 years of age or older. The median age was 42 years. For every 100 females, there were 101.0 males. For every 100 females age 18 and over, there were 98.7 males. The median income for a household in the town was $37,396, and the median income for a family was $46,786. Males had a median income of $29,511 versus $23,417 for females. The per capita income for the town was $25,171. About 7.0% of families and 9.3% of the population were below the poverty line, including 15.2% of those under age 18 and 5.6% of those age 65 or over.
Wilmington experiences a humid continental climate with warm, humid summers and cold winters. While snowfall can vary greatly from year to year in nearby towns like Bennington and Brattleboro, Wilmington's snowfall is consistently heavy each year because of its elevation in the Green Mountains' high country.
August 28, 2011 – The town of Wilmington, and the state of Vermont, was hit by Tropical Storm Irene. 13 inches of rainfall came through the course of 10 hours, comparable to dumping 26 swimming pools on every acre of land. The rivers flooded over their banks washing away buildings, destroying downtown businesses and inventory, and displacing families from their homes. In terms of infrastructure, Wilmington was the hardest hit town in the entire state. Almost immediately after the storm subsided residents began the work of cleaning up and figuring out how to turn this devastating tragedy into a blessing. Within days the National Guard was repairing washed out roads, businesses were getting cleaned out, and fund raising began to help affected people and businesses to get back on their feet. The Wilmington Flood Relief Fund, chaired by Adam Palmiter, raised just shy of $500,000 to benefit local businesses and flood relief throughout the Deerfield Valley. By the date of the one year anniversary, the town was again thriving with many businesses back better than ever, tourists excited to shop locally, and new opportunities on the horizon thanks to a broader outlook in the years to come.
Vermont snowfall record
Wilmington is in the heart of the Southern Vermont snowbelt. This snowbelt lies mainly within the southern Vermont portion of the Green Mountain National Forest and includes the high elevation Southern Vermont towns of Woodford, Searsburg, Wilmington and Marlboro. Between February 24 and February 27, 2010, Wilmington received a record of snow. Over of snow fell during this February 2010 blizzard. Snowfall amounts of up to were reported for Wilmington, West Dover and the surrounding towns. The February 2010 blizzard in Wilmington and West Dover appears to be the single storm snowfall record for anywhere in the state of Vermont in Vermont weather record keeping history. The previous single storm snowfall record was between March 2–5, 1947 in Readsboro, Vermont.
