Just a week after destructive floods battered Vietnam, the country is now preparing for the arrival of Tropical Storm Khanun.

The storm is crossing the Leizhou Peninsula and is currently located around 300 kilometres to the east of Hanoi.

Khanun was the 20th typhoon this year, having made landfall in southern China on Monday morning (local time) in Xuwen county in Guangdong province. It has since weakened significantly, and a final warning for the storm is expected to be issued by the end of Monday.

The winds may not be a problem, but Khanun is expected to spread heavy rains across southwest China into the north and central areas of Vietnam.

Rainfall totals have exceeded 100mm in places as the storm brushed the coast of southern China. Haikou recorded 123mm of rain on Sunday. Meanwhile, Shanwei notched up 135mm in the same 24-hour period.

Vietnam's disaster prevention agency said 72 people died in last week's floods. According to the government and state-run Vietnam Television, those floods were the worst in decades.

Thousands of homes were submerged. Another 200 houses collapsed, and several towns remain cut off by the floodwaters. The floods also damaged more than 22,000 hectares of rice fields.

The torrential rains associated with Tropical Storm Khanun will exacerbate those floods, with the country braced for another spell of widespread disruption across the north over the next few days.