According to the United States Census Bureau, the township has a total area of, of which, of it is land and of it is water.
Demographics
As of the census of 2010, there were 4,225 people, 2,529 households, and 1,839 families residing in the township. The population density was 79.7 people per square mile. The racial makeup of the township was 91.4% White, 3.9% African American, 0.1% Native American, 0.9% Asian, 1.6% from other races, and 1.9% from two or more races. Hispanic or Latino of any race were 5.2% of the population. There were 2,529 households, out of which 27% had children under the age of 18 living with them, 48.5% were married couplesliving together, 8.6% had a female householder with no husband present, and 39.3% were non-families. 28.7% of all households were made up of individuals, and 13.9% had someone living alone who was 65 years of age or older. The average household size was 2.3 and the average family size was 2.9. In the township the population was spread out, with 20.2% under the age of 18, 6.6% from 18 to 24, 27.4% from 25 to 44, 26.1% from 45 to 64, and 16.0% who were 65 years of age or older. The median age was 45.8 years. For every 100 females, there were 98.8 males. For every 100 females age 18 and over, there were 94.3 males. The median income for a household in the township was $54,332, and the median income for a family was $59,230. Males had a median income of $37,291 versus $33,474 for females. The per capita income for the township was $27,157. About 7.2% of families and 9.4% of the population were below the poverty line, including 12.4% of those under age 18 and 4.2% of those age 65 or over.
Climate
According to the Trewartha climate classification system, Barrett Township has a Temperate Continental climate with warm summers, cold winters and year-around precipitation. Dcbo climates are characterized by at least one month having an average mean temperature ≤, four to seven months with an average mean temperature ≥, all months with an average mean temperature < and no significant precipitation difference between seasons. Although most summer days are comfortably humid in Barrett Township, episodes of heat and high humidity can occur with heat index values >. Since 1981, the highest air temperature was on 07/15/1995, and the highest daily average mean dew point was on 08/01/2006. July is the peak month for thunderstorm activity which correlates with the average warmest month of the year. The average wettest month is September which correlates with tropical storm remnants during the peak of the Atlantic hurricane season. Since 1981, the wettest calendar day was 6.15 inches on 09/30/2010. During the winter months, the plant hardiness zone is 5b with an average annual extreme minimum air temperature of. Since 1981, the coldest air temperature was on 01/21/1994. Episodes of extreme cold and wind can occur with wind chill values <. The average snowiest month is January which correlates with the average coldest month of the year. Ice storms and large snowstorms depositing ≥ 12 inches of snow occur once every couple of years, particularly during nor’easters from December through March.
Ecology
According to the A. W. Kuchler U.S. potential natural vegetation types, Barrett Township would have a dominant vegetation type of Appalachian Oak with a dominant vegetation form of Eastern Hardwood Forest. The peakspring bloom typically occurs in late-April and peak fall color usually occurs in mid-October. The plant hardiness zone is 5b with an average annual extreme minimum air temperature of.
