The mystery of the disappearing autumn has people living in northern China baffled. Only days ago, they were happily wearing T-shirts and skirts; but now, thick coats and down jackets are out in force. Fall was just a fleeting feeling, and indications are that this weather pattern could become the norm in the future.

According to available meteorological data, the transitional period between summer and winter is shrinking in China, with autumn arriving later than usual and ending sooner.

Delayed autumn

While southwestern cities such as Guiyang in Guizhou province, Chengdu in Sichuan province, and Chongqing still enjoy around 70 to 80 days of cool autumn weather — with Guiyang topping the list at 79 days — people living in the north barely experience 50 days of autumn, said Weather China, a website under the China Meteorological Administration.

An analysis of long-term weather data from the website reveals that since 1991, autumn has been delayed across much of the country. Cities such as Zhengzhou in Henan province, Ningbo in Zhejiang province, and Shenzhen in Guangdong province now see autumn arrive more than 10 days late on average, while Nanjing in Jiangsu province, Fuzhou in Fujian province, and other places have recorded delays of five to nine days.

Studies show that across China, the duration of winter, spring and autumn is shrinking, and these shifts are more prominent in northern and eastern regions, the website said.

"Maybe there will be only three seasons in the future," a netizen said on social media platform Sina Weibo. "A trench coat feels like the most impractical outfit in Beijing, "another said, indicating the sharp transition from cool to cold weather in the capital.

Wang Weiyue, a meteorologist at Weather China, said that given global climate change, rising temperatures across various regions have become an indisputable fact, and this delays the onset of autumn, affecting agricultural production and people's daily lives.

Sudden chill

This year's northern chill has arrived abruptly.

Li Duo, a senior engineer at the National Climate Center, said that since October, several regions, including parts of Heilongjiang province, the Inner Mongolia autonomous region, Hebei province, and the Xinjiang Uygur autonomous region, were 1 C to 2 C colder than usual.

The recent temperature drop in northern China was mainly due to two major cold-air events between Oct 9 and 10 and Oct 18 and 19, Li said.

The China Meteorological Administration forecasts that much of northern China will remain colder than average through Friday, while southern regions will also see temperatures drop by up to 5 C by the end of the month.

Experts advised residents to dress warmly, stay alert to weather changes, and ventilate indoor spaces when using heating to avoid carbon monoxide-related risks.

zhaoyimeng@chinadaily.com.cn