Koganei (小金井市, Koganei-shi) is a city located in the western portion of the Tokyo Metropolis, Japan. As of 1 March 2021[update], the city had an estimated population of 123,698 in 61,832 households. The total area of the city is 11.30 square kilometres (4.36 sq mi) so the population density is about 11,000 persons per km².[1] Koganei is approximately at the center of Tokyo metropolis, and is located about 20 kilometers west of Shinjuku, where Tokyo Metropolitan Government has its headquarters. It is flanked on the north and the south by two large parks. To the north is Koganei Park, which includes the Edo-Tokyo Open Air Architectural Museum, a branch of the Edo-Tokyo Museum located in Ryōgoku, Tokyo. To the south are Nogawa Park and Tama Cemetery. The city has an elevation of between 40 and 70 meters above sea level. Koganei has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall. The average annual temperature in Koganei is 14.0 °C. The average annual rainfall is 1647 mm with September as the wettest month. The temperatures are highest on average in August, at around 25.5 °C, and lowest in January, at around 2.6 °C.[2]