The typhoon is packing top sustained winds of 220 kilometers (137 miles) per hour, according to the Hong Kong Observatory, which is equivalent to a Category 4 hurricane on the five-step . The system was 340 kilometers southeast of the city as of 4 p.m. local time.

Ragasa has caused major flight disruptions, and suspension of school classes and business activities across southern China after skirting northern Philippines on Monday. The weather bureau has issued its third-highest storm warning, and is assessing the need to raise it further, potentially to the highest level.

The current storm warning level in place is dubbed signal No. 8, while the most severe alert, known locally as a T10, means hurricane-force winds are present or expected. The weather will be “persistently adverse” on Wednesday, with gale- to storm-force winds prevailing, the Hong Kong Observatory said.

Ragasa has forced some conferences and forums scheduled for Wednesday and Thursday online, including a gathering on fixed income and currencies, while several delegates have pulled out of an aviation conference. Loan bankers also rushed to get paperwork physically signed to keep deals moving along.

In 2018, Mangkhut brought damaging winds and record-breaking storm surges to Hong Kong, with the weather agency estimating it caused total economic losses including insurance claims of HK$4.6 billion ($592 million). The city may see a similar storm surge from Ragasa, according to forecasters.

“The only thing that will stop this storm is land,” the U.S. Navy’s Joint Typhoon Warning Center said in an earlier advisory. Ragasa will slam Hong Kong with gale- to storm-force winds as the storm passes to the south of the city, it added.

Passenger flights in and out of Hong Kong will be suspended for 36 hours from 6 p.m. local time on Tuesday. Almost 50% of the 1,098 passenger and cargo flights due to depart and arrive at the airport today have already been axed, according to data compiled by Webb-site.com.

Airports in Shenzhen and Macau will also close for an unspecified period, and all rail services in China’s Guangdong province will be suspended on Wednesday. Cities including Zhuhai, Jiangmen and Foshan—the country’s “aluminum capital”—also suspended classes and work.

Across Hong Kong, businesses and residents are taking steps to prepare, with some grocery stores cleared of food items such as fresh vegetables. Many shop and apartment windows are also taped up with giant X’s, a practice thought to protect against flying debris, but a measure the U.S. National Oceanic and Atmospheric Administration says is a waste of time and tape.

In Taiwan, thousands of households lost power, and offices and schools were closed in some southern cities, while nearly 25,000 people were evacuated across the Philippines’ main Luzon island. Ragasa skirted the northern part of the archipelago and is now churning in the South China Sea.

The storm is expected to track toward Vietnam after clipping southern China, and the Southeast Asian nation has put more than 300,000 military personnel, 8,000 vehicles and six aircraft on standby for the cyclone.