70 Years of Meteorological Data Tells You: Is Autumn Really Getting Shorter?
Cold Wave Hits, Temperatures Across Most of the Country to Drop by 6-10℃, Many Places “Snap” into Winter
Hangzhou, Wuxi, and other places bid farewell to autumn and enter winter overnight. This year, Hangzhou entered winter a week earlier than usual, making autumn seem even shorter.
Meanwhile, Guangzhou and Shenzhen finally ended their over 200-day extended summer and welcomed autumn. For people in Guangdong this year, complaints like “wearing a T-shirt from March to November” and “my short-sleeved shirts are wearing out” were frequently heard. Even when autumn finally arrived, netizen @Bingqing Xiaobaitu commented, “In just a couple of days, we’ll be entering winter again.”
From a sensory perspective, autumn seems to be getting shorter, with winter quickly following the hot summer. People in some cities are also smelling the fragrance of osmanthus and admiring the red maples and ginkgoes later than usual.
The Paper’s Data Class, referring to the latest 2022 meteorological industry standard “Classification of Climatic Seasons”, estimated the length of the four seasons in 31 provincial capitals (excluding Hong Kong, Macao, and Taiwan) from 1955 to 2024, attempting to answer whether autumn is really getting shorter and delayed.
Autumn is Shortening in Guangzhou, Haikou, and Other Places
In meteorological terms, the four seasons are usually divided based on the average temperature of five consecutive days, with temperatures below 10℃ indicating winter, above 22℃ indicating summer, and between 10℃ and 22℃ indicating spring and autumn. Combining the usual seasonal transition dates and the average length of the four seasons, we obtained the number of days for spring, summer, autumn, and winter in 31 provincial capitals.
Data over the past 70 years show that autumn is shortening in some cities, such as Guangzhou and Haikou.
Compared to the autumn days from 1955 to 1964, autumn in Guangzhou has shortened by 19.3 days in the last decade, followed by Haikou with a shortening of about 13 days. Autumn in some northern cities is getting longer, such as Jinan and Zhengzhou, where autumn has lengthened by more than 5 days.
An article published by China Weather Network in 2019 also found similar trends: Nationwide, for the transitional seasons of spring and autumn, the number of areas where they are getting longer and shorter is roughly equal—more places in the north are getting longer, while more places in the south are getting shorter.
This is mainly influenced by climate change. A paper published in Geophysical Research Letters studied the four seasons in the mid-latitude regions of the Northern Hemisphere and found that from 1952 to 2011, the average number of summer days increased from 78 to 95, while winter days decreased from 76 to 73. Spring and autumn also decreased from 124 to 115 days and from 87 to 82 days, respectively.
Difficulty in Entering Autumn is Unfolding
Summer has become exceptionally long.
In 2024, Guangzhou ended its 240-day summer on November 18, and Shenzhen ended its 242-day summer on November 19, both breaking historical records. Some joked, “My short-sleeved shirts are wearing out.”
Other provincial capitals have also generally experienced longer summers. In 2024, Chengdu entered summer on May 13 and autumn on September 29. The 139-day summer was the longest in Chengdu since 1961. In contrast, the summer of 1961 in Chengdu was only 102 days.
The lengthening of summer has delayed the arrival of autumn. To enjoy the fragrance of osmanthus, the rustling of red maples, and the brilliance of ginkgoes, one has to wait longer.
Zhu Huafang, a senior engineer at the Shanghai Botanical Garden, said in an interview with News Morning Post that due to the exceptionally high temperatures during the extended summer this year, the osmanthus flowers were delayed in blooming.
Around September 29, 2024, the early silver osmanthus in the Shanghai Botanical Garden finally bloomed, marking the latest bloom recorded in the garden’s phenological records, about 2-3 weeks later than the normal flowering period.
Compared to the usual autumn entry dates from 1991 to 2020, Shijiazhuang has had the most delayed autumn entry in the last decade, with an 8-day delay. This is followed by Taiyuan, Guangzhou, Shanghai, and other places.
Similar situations have been observed with red maples in Japan. According to the Japan Meteorological Agency’s predictions, this year is the latest for autumn foliage in recorded history. In Kyoto, Japan, the best time to view autumn foliage is usually around November 28, but in 2024, it was 11 days later.
Besides the delayed viewing periods for red maples, ginkgoes, osmanthuses, and other plants, more severe consequences may also occur.
A study using model estimations shows that by 2050, the survival range of the Aedes aegypti mosquito, which carries the dengue virus, will expand northward at a rate of 2-6 kilometers per year in North America and China.
Furthermore, as temperatures rise, the start of the pollen season is appearing earlier and lasting longer. Spring and late summer to early autumn in northern China are the most challenging times for pollen allergy patients—pollen causes them to sneeze, tear up, and even develop facial swelling. In the future, pollen allergy patients may face even more difficulties.
