The number of ambulance dispatches in Tokyo from January to July grew 4.4% from a year ago to 542,256, the highest for the seven-month period since the statistics began in 1936, according to the Tokyo Fire Department.
The result is attributable mainly to an increase in heatstroke cases.
On July 8, when Tokyo logged a high temperature of 36 degrees Celsius, the daily number of ambulance dispatches came to 3,372, the highest level so far this year and the second-highest daily number on record, according to the department.
Japan's average temperature last month hit the highest level for July since statistics began in 1898, according to the Meteorological Agency.
This July accounted for half of the top 10 busiest days in terms of ambulance dispatches, according to the department.
The total number of people taken to hospitals by ambulance due to heatstroke this year had reached 4,183 as of July 28, growing faster than last year.
The department issued an ambulance shortage alert 19 times last month, up from just five a year before.
The department encourages citizens to stay hydrated and use air conditioners to prevent heatstroke, calling for dialing #7119 to get advice on whether to call an ambulance.