Hong Kong was preparing to shutter businesses as Typhoon Hato drew closer to the city, with Cathay Pacific Airways Ltd. scrapping flights and the local observatory warning it may raise the third-highest storm signal at midnight local time.

The tropical cyclone has continued to intensify in the past few hours and may pass within 100 kilometers south of the global financial center, posing a “considerable threat” to the city, the Hong Kong Observatory said. The No. 8 Gale or Storm Signal may be increased around midnight, it said, after the Strong Wind Signal No. 3 was issued at 6:20 p.m. Hato, named after the Japanese word for pigeon, was estimated to be about 410 kilometers east-southeast of the city and forecast to move toward the coast of Guangdong at about 25 kilometers per hour, according to the observatory.

Cathay Pacific said a majority of flights to and from Hong Kong between 6 a.m. and 5 p.m. on Wednesday are cancelled. Most businesses close and much of the city’s public transport starts to shut down after the No. 8 signal is hoisted.

The storm may also stop trading in the world’s fourth-largest equity market. Hong Kong Exchanges & Clearing Ltd. will cancel pre-market trading if the No. 8 signal is in force between 7 a.m. and 9 a.m., according to its trading rules. The morning session will be scrapped if the warning is still in effect at 9 a.m. and trading will be closed for the day if not lifted by noon. The last time the city had to scrap full-day trading was in October 2016, when Typhoon Haima prompted schools to close and airlines to suspend flights.

The observatory warned that weather in Hong Kong is deteriorating gradually and there will be heavy squally showers. There may be serious flooding in some low-lying areas as the storm coincides with a high tide on Wednesday morning.

People stuck at home may have to fend for themselves. Food delivery service provider Foodpanda said in a statement to clients that orders will be canceled if the No. 8 signal is still up before 8 a.m. on Wednesday.