The Observatory says it will issue the No.8 Gale or Storm Signal at or before 1:40pm on Wednesday.

At 11am, Severe Tropical Storm Nalgae was estimated to be about 200 kilometres southeast of Hong Kong and is forecast to move northwest at about 10 kilometres per hour, edging closer to the vicinity to the west of the Pearl River Estuary.

Under the combined effect of Nalgae and the northeast monsoon, local winds are expected to gradually strengthen in the afternoon and showers are expected to become more frequent.

The Education Bureau had earlier announced the suspension of all classes.

The government also advised members of the public with long or difficult home journeys, or those who have to return to outlying islands, to head home now.