A relatively small typhoon that developed southeast of Minami-Daito Island, Okinawa Prefecture, may strike mainland Japan on Friday, becoming the first to do so this year, according to the Meteorological Agency.
Agency officials called on people living in the western part of the country to keep watch on the storm's movement.
It is only the fourth typhoon this year -- the fewest to develop by this time of the year since the agency started tracking tropical cyclones in 1951.
On average, 14 to 15 typhoons usually develop by August, with five or six taking place in August alone. But the El Nino phenomenon lowered water temperatures on the sea surface in areas where typhoons spawn, delaying their occurrence, agency officials said.
The first typhoon this season formed on July 9 -- the latest on record since 1951.