BEIJING - While hundreds of millions of Chinese students are counting down the final hours to the end of their summer vacations on Thursday, the recent hot weather has given four extra days off to 5 million students and teachers in primary and high schools in Chongqing.

"I like having a super long summer vacation," said Qian Qian, a 6-year-old student in Xingguang Primary School in northern Chongqing on Wednesday. "It even makes the heat not seem so bad."

She said she plans to spend her extra vacation days living with her grandma, whose house is on a nearby mountain, in a place that is cooler than the city.

Chongqing's education committee issued an urgent circular on Tuesday saying the first day of classes for all local primary and high school students will be moved back from Thursday to Monday. The decision was made to protect the students' health.

If the extreme heat continues until Monday, primary and high school students may be allowed to stay out of it by continuing their "hot weather vacation", the circular said.

The education authority also asked the schools to cancel large events they had planned and adjust the schedule for when students will exercise outdoors. The request also applied to military training conducted at high schools and universities.

Since August 15, Chongqing has been subjected to several days of extreme heat; the thermometer has registered as high as 42 C.

The city's weather forecast bureau issued an orange alert for high temperatures, the second highest alert possible in China, on Aug 27 and 28.

On Monday, the temperature again exceeded 40 C, and the extreme heat is expected to extend into the weekend, the bureau said on its official website.

"I want to praise the education department for making this responsible decision to push back the first day of classes," said Li Jie, a mother of a primary school student in Chongqing.

She learned the news on Wednesday on an instant message service used by the school to let parents communicate more quickly with teachers.

"Even though the classrooms have air conditioners, the little kids are still in danger of suffering heatstroke when they eat in the student canteen or exercise on the school's playground," she said.

"Parents should become more aware of the dangers their children face: drowning, heatstroke, fires, traffic accidents," said a teacher at Xingguang Primary School, who declined to provide his full name.

"Children are always exposed to dangers during summer vacations."

For boarding school students who have already returned after the summer break, Chongqing Railway Middle School has opened its student canteen, library and computer lab.

The Chongqing No 11 Middle School has meanwhile opened its gym, library, dormitory and classrooms for more than 100 students who have returned from the countryside.