It's the first typhoon to affect Korea this year.
Typhoon Khanun landed in Korea earlier than expected, hitting the Seoul metropolitan area before 9 am on Thursday.
The heavy rain and powerful winds from Wednesday night into Thursday morning even caused flight cancellations and delays.
At least two international flights from Incheon were cancelled and some 90 domestic flights were cancelled by Thursday morning.
Officials say passengers should check with their airline before heading to the airport.
Morning commuters were also disrupted as several roads around the capital like in Yangjae and Olympic Highway. were blocked.
In the Incheon area, the typhoon brought strong winds of up to 12 meters per second, disrupting subway services.
Khanun's heavy downpours started on Jeju Island, Wednesday afternoon and moved up toward the West Sea on Thursday.
Even though the heavy rain and winds have now weakened with storm advisories lifted at 10AM the accompanying rain is expected to continue into Friday morning.
The areas significantly affected by Khanun are the northeastern regions of Korealike in Gyeonggi Province with rain expected to fall at a rate of about 20 millimeters per hour and winds as strong as 20 meters per second.
Officials are asking residents to be careful of falling signs or debris.. until the typhoon fully passes over.
Connie Lee, Arirang News.