Typhoon Bolaven hammered into Japan's southernmost islands Monday, forcing flight cancellations, the closing of an oil refinery and one of the highest weather alerts at the Kadena U.S. military base on Okinawa.

As much as 50 millimeters (2 inches) of rain per hour could fall in parts of Okinawa and Kyushu, Japan's weather agency said. Landslide and high wave warnings were issued as wind gusts reached 213 kph. Video by Japan's public broadcaster NHK showed tree limbs being snapped in Naha, Okinawa's capital.

"My yard is getting filled with water," said Sayaka Higa, who was forced to stay home from her job as a spokeswoman at the U.S. military's Kadena Air Base about 18 kilometers north of Naha.

Japan Airlines 125 domestic flights to Okinawa and surrounding islands, the carrier said on its website. Some international flights are also affected. All Nippon Airways also canceled flights to the region and advised passengers to check with the airline.

Bolaven was about 410 kilometers (255 miles) north- northwest of Naha, a city of 321,000, at 2:45 p.m. local time, according to the Japan Meteorological Agency. It had sustained winds of 148 kilometers per hour (92 mph), making it a Category 1 storm, the weakest on the five-step Saffir-Simpson Hurricane Wind Scale.