All kindergartens, primary schools and special schools are suspended today amid the big freeze, with about 510,000 children given an unprecedented cold- day leave.
Temperatures are expected to drop even lower today.
This comes as sub-zero temperatures were recorded at Tai Mo Shan yesterday, with firefighters scrambling to rescue dozens trapped at the city's highest point, as well as on Kowloon Peak and Lantau Peak.
"As the abnormal weather is expected to continue, classes of kindergartens, schools for children with physical disability, schools for children with intellectual disability and primary schools will be suspended tomorrow," the Education Bureau said last night.
"These schools, however, should keep their premises open and implement contingency measures to look after students who need to return to school."
It added: "As regards secondary schools, the Education Bureau calls on parents to prepare enough warm clothes for students.
"Schools are required to pay attention to the physical condition of their students and to consider suspending outdoor activities in order to safeguard the health of students."
Special schools with secondary students have not suspended classes.
There are 1,549 kindergartens and primary schools, including English Schools Foundation and international schools, and 61 special schools.
But directly subsidized Good Hope School at Clear Water Bay Road announced all its primary and secondary sections will be suspended today.
The observatory said last night that the rain band affecting the coast of Guangdong is weakening but temperatures on high ground remain below zero degrees with the chance of ice and freezing rain. There will be a few rain patches with small ice pellets in some areas.
Temperatures today will range from 3 to 9 degrees Celsius.
Lows until Wednesday will be 7 to 11C before rising on Thursday, when temperatures will range from 15 to 17C.
The former head of the Education and Manpower Bureau from 1995 to 2000, Joseph Wong Wing-ping, believed it was the first time the Education Bureau had suspended classes because of low temperatures.
The class suspension was made after the Hong Kong Professional Teachers' Union yesterday called for a suspension of classes due to the cold and wet weather. But education lawmaker Ip Kin-yuen said he did not understand why the bureau was not suspending all special schools, such as schools for children with visual and hearing impairment.
The vice chairman of the Hong Kong Aided Primary School Heads' Association, Sin Kim-wai, said the decision could safeguard primary students as some of them need to take school buses and the roads are slippery, which may endanger their safety.
Federation of Parent-Teacher Associations of Hong Kong Eastern District chairman Raymond Jao Ming said it was a reasonable and understandable decision as he had heard some outdoor activities had already cancelled due to bad weather.