Hong Kong raised its highest black rain signal on Thursday, prompting schools to close and some businesses to halt as it asked residents to take shelter and be on guard for severe flooding.

Heavy rain exceeding 70mm in an hour is ⁠likely to continue, the observatory ​said at 12.55pm local time (0455GMT), ⁠on its website. It is the second time the black warning signal has ⁠been hoisted this year; the first occurred more ​than ⁠a week ago ‌on 8 June.

The financial hub, along with much of southern China, has been soaked for several days now due to an active southwest monsoon and a lingering trough of low pressure.

Intense gusts may continue to affect Hong ⁠Kong, with wind strength of around 80km (50miles) per hour recorded in the city's southwestern district of Tai O, the observatory said.It comes ahead of the Dragon Boat Festival on Friday, which gives residents a three-day weekend, when many are expected to travel.

Authorities across the ​border in Shenzhen, mainland China, hoisted ‌the red rain signal ⁠and urged residents to stay away from ⁠low-lying, waterlogged and what it called "other dangerous areas.

"There was an increased risk of mountain floods, landslides and other disasters, they said.

The Rthk.hk news reported that a special announcement on flooding in the northern New Territories was also issued earlier, with rain especially heavy in Yuen Long, Sheung Shui and Ta Kwu Ling.

Childcare and elderly service centres, as well as rehabilitation service units and vocational training centres will remain open during their normal operating hours to take care of those in need, it reported, quoting the Social Welfare Department.