Have you ever felt like spring disappears before you can enjoy it, or that autumn barely arrives before winter sets in? Many people may feel the same way in Japan. Recent data from the Japan Meteorological Agency indicates that Japan's climate is gradually changing.
In Tokyo, the average temperature has risen by approximately 1.3°C over the past 100 years. This rate of increase is higher than the global average of about 1.1°C. As a result, the transitional seasons—spring and autumn—are becoming shorter, while summer and winter are gradually extending.
For example, summer-like temperatures now tend to come earlier each year. In 2024, central Tokyo recorded a temperature of 26.1°C on March 31. This was 32 days earlier than the average in the 1970s, indicating that the period of mild spring weather is becoming shorter.
Autumn is also becoming hotter. Between September and October, the number of days exceeding 30°C increased from an average of 6.8 days in the 1970s to 22 days in 2024. It is clear that hot days are becoming more frequent even in autumn.
The graph below shows two trends since 1970:
- The number of days exceeding 30°C between September 1 and October 31
- The first day of the year when the temperature exceeds 25°C
Although there are year-to-year variations, the overall trend indicates that summer is starting earlier and hot days in autumn are becoming more frequent.
