Japan's average temperature is expected to rise 2 to 3 degrees by 2100, while the average global temperature will rise by about 2.5 degrees, the Meteorological Agency said Friday.

In a report on abnormal climates, the agency said the average temperature has risen by 1.06 degrees in Japan and by 0.74 degree globally during the past century.

The report also states that heavy rainfall is now more frequent across the globe.

Comparing the 30-year period ending in 2004 with the 30-year period ending in 1930, the number of days in Japan with at least 200 mm of rainfall has increased 1.5-fold, it says.

"It is possible that global warming has increased the amount of moisture in the air," the agency said in the report, which it compiles roughly every five years.

In its 1999 report, the agency said the average temperature had jumped 1 degree in Japan and 0.6 degree globally during the previous century.

The rate of increase has accelerated in recent years, according to the latest report.

The agency tied rising temperatures in major Japanese cities to the so-called heat island effect. This phenomenon involves urban areas becoming several degrees warmer than rural areas because of the high concentration of buildings that trap heat.

The average temperature has climbed by 3 degrees in Tokyo, 2.7 degrees in Nagoya and 2.6 degrees in Kyoto over the past century, exceeding rises in small and midsize cities by 1 to 2 degrees, the report says.