At least four people died earlier today amid cold temperatures, as the observatory forecasts the cold spell to continue until Wednesday.
Several elderly people fainted at their homes and subsequently died.
They included an 80-year-old man who fainted in his residential flat at Mei Foo Sun Chuen this morning, and another 96-year-old woman who lived in a Shau Kei Wan elderly home.
A 32-year-old woman was also found unconscious in Tseung Kwan O Kin Ming Estate at about five this morning. She later died.
A man, whose age has yet to be confirmed, collapsed outside a Quarry Bay building past midnight.
At least another five people died yesterday.
The cold weather warning is still in effect in Hong Kong, where the temperature in most places has dropped to about 10 degree Celsius, Hong Kong Observatory said.
It estimated that the low temperature will persist until Wednesday, with the lowest temperature being 9 degrees. The city will be warmer later this week, with temperatures ranging between 14 and 20 degrees.
The Home Affairs Department has opened 18 temporary cold shelters for people in need. The centre remains open until the cold weather warning hangs down.
The Centre for Health Protection also reminded the public to take care of the elderly and those with chronic medical conditions.