Tokyo Air Masses

As mentioned before, Tokyo lies in the humid subtropical climate zone. Because Japan is an island in the in the Pacific Ocean, it has some interesting weather patterns. In the summer, Tokyo is influenced by the maritime tropical air mass that are generated over warm coastal waters on the east coast.  In the fall, winter and spring maritime tropical and continental polar air masses interact which creates frequent midlatitude cyclones with cold and occluded frontal activity.  

source: csulb.edu
Air Mass Map

These air masses allow for Tokyo to get an average of 40-80 inches of precipitation a year.  The summer months get more precipitation than the winter months because of the effects of the Asian monsoon.  

source: Wikimedia Commons
Topographic Map of Japan

Tokyo is located in the central part of the archipelago (chain of islands) of Japan.  There are several mountains surrounding Tokyo including; Mount Mitake, Mount Kumotori, Mount Mihara, and Mount Takao.  There are two rivers that run through Tokyo, the Tama river and  Samuda river. Tokyo's topography allows for high levels of precipitation because of the very mountainous terrain.  



source:  www.jma.go.jp/en/g3/
Tokyo Weather Map


This is a current weather map of Tokyo for 6pm on November 1st.  It shows developing lows coming in from the southeast towards Tokyo, which means clouds will roll in over the city.  Since Japan is an island and in the middle of major oceanic currents,  a dense fog could settle over Tokyo.