According to the United States Census Bureau, the CDP has a total area of, of which, of it is land and of it is water. The total area is 7.16% water. Kahului is directly adjacent to Wailuku located on the west side of town, and to Spreckelsville on the east.
Climate
Kahului has a hot semi-arid climate zone with a dry summer season, due to its location on the leeward side of Maui, relative to the trade winds. The normal monthly mean temperature ranges from in February to. On average, there are 21 nights annually with a low below and 25 days with a high at or above ; readings of or higher are far rarer, occurring on average once every five years. Temperature records range from on January 20, 1969 up to on August 31, 1994 and August 22, 2015. The record cool daily maximum is on February 28, 1990, while, conversely, the record warm daily minimum is on October 8 and 17, 1979. Normal annual rainfall is spread over an average 95 days, but observed annual rainfall has ranged from in 1908 and 1998 to in 1989. The wettest month on record is January 1980 with, while the most rain to occur in a single calendar day is on December 21, 1955. The most recent month without measurable rain is October 2013 with trace amounts, and the last without any rain is June 1957. The town is also one of the windiest places in the U.S. averaging 13.7 mph per year.
Demographics
As of the 2000 Census, there were 20,146 people, 5,880 households, and 4,421 families in the CDP. The population density was 1,328.7 people per square mile. There were 6,079 housing units at an average density of 400.9 per square mile. The racial makeup of the CDP was 10.06% White, 0.24% Black or African American, 0.27% Native American, 53.62% Asian, 9.91% Pacific Islander, 1.47% from other races, and 24.42% from two or more races. 8.75% of the population were Hispanic or Latino of any race. There were 5,880 households, 34.9% had children under the age of 18 living with them, 51.9% were married couples living together, 16.6% had a female householder with no husband present, and 24.8% were non-families. 20.3% of households were one person and 11.9% were one person aged 65 or older. The average household size was 3.29 and the average family size was 3.76. The age distribution was 25.8% under the age of 18, 9.2% from 18 to 24, 27.6% from 25 to 44, 20.7% from 45 to 64, and 16.7% 65 or older. The median age was 36 years. For every 100 females, there were 97.3 males. For every 100 females age 18 and over, there were 95.8 males. The median household income was $46,656 and the median family income was $52,610. Males had a median income of $30,659 versus $26,282 for females. The per capita income for the CDP was $18,049. 11.8% of the population and 9.7% of families were below the poverty line. Out of the total population, 14.8% of those under the age of 18 and 11.6% of those 65 and older were living below the poverty line.
