The observatory says it will keep the Standby Signal No 1 in place for most of Monday but is unlikely to issue a higher warning as Severe Tropical Storm Haikui approaches.

The storm is expected to make landfall in eastern Guangdong or southern Fujian on Tuesday.

At 11am, Haikui was estimated to be about 560 kilometres east of Hong Kong and was forecast to move west-northwest at about 12 kilometres per hour across the Taiwan Strait.