Sandstorms from northern China and Mongolia are forecast to reach Tokyo this weekend, according to the Japan Meteorological Agency.

Yellow desert dust from China's northwestern provinces and Mongolia will reach Tokyo at about 3 a.m. Saturday and remain until Sunday morning, according to the agency's website. Visibility in the Japanese capital will be reduced to 10 km from 40 km at normal levels, the agency said.

The sandstorm, which reached the southern island of Kyushu around noon today, will coincide with graduation ceremonies of some Tokyo schools and universities scheduled to be held Saturday. Tokyo is forecast to be fine and sunny tomorrow, with temperatures expected to reach a maximum of 17 degrees.

Measurements of PM2.5, fine airborne particulates that pose the largest health risks, are not likely to rise significantly due to the sandstorms, Takahisa Goto, an official at the environment ministry said by phone today. Japan's environment ministry last week said local authorities should issue warnings when concentrations rise to an average of 70 micrograms per cubic meter per hour.

Japan considers PM2.5 readings of 35 micrograms per cubic meter to be safe.