Top 10 weather and climate events in 2020 unveiled

Source: China Meteorological News Press Date: 2021/01/12

Recently, the selection result of the top 10 domestic and global weather and climate events in 2020 has been unveiled.

The selection results of the top 10 weather and climate events in China have reflected the major features of weather and climate conditions in 2020 in China: firstly, more days of rainstorm with strong intensity and high overlapping of rain coverage in the flood season; secondly, more days of high temperature and staged meteorological drought in many regions; thirdly, early onset, high frequency and strong intensity of severe convective weather; fewer generations and landfalls of typhoons in China in 2020.

Let's have a look.

Top Ten Domestic Weather and Climate Events

Longest plum rain period and heaviest rainfall in middle and lower reaches of the Yangtze River in history

In 2020, plum rain period started earlier and ended later in southern portions of China like middle and lowered reaches of the Yangtze River. The plum rain period persisted longer with heavier rainfalls and frequency outbreaks of extreme rainfall events. Rainfall during the plum rain period reached 759.2 mm, which was about 1.2 times heavier than normal, and was the heaviest since 1961.

Historical changes of rainfall during the plum rain period (the year 1961 to 2020, the yellow column representing the year 2020)

3 typhoons affecting Northeast China within half a month rarely seen in history

From the second half of August to the first half of September, within half one month, the 8th typhoon Bavi, the 9th typhoon Maysak, and the 10th typhoon Haishen in 2020 successively gripped Northeast China, which had unseen since 1949. Affected by the typhoon, many flights and trains were cancelled in many places; serious road waterlogging happened; classes were suspended in many elementary and middle schools; people’s life was affected to some degree.

track of typhoon Bavi, Maysak and Haishen

No typhoon generation in July for the first time in history

In July 2020, there was no typhoon generation and landfall in the South China Sea and the West Pacific, which was the first occurrence since 1949. The absence of typhoons in July triggered more days of high temperature in summer, and more severe drought conditions in South China.

Historical changes of the number of typhoon generated in July from the year 1990 to 2020

Heavy rain and severe flood season condition in summer

From June to August in 2020, average rainfall was 14.7% heavier than that in normal years, which ranked the second since 1961, second only to that in 1998. In all river basins of China, rainfall in the Yangtze River Basin and the Yellow River Basin was the heaviest respectively since 1961.

On June 29, Xiaolangdi Dam of the Yellow River discharged the flood water.

Monitoring image of the water body changes in the main body and neighboring waters of Poyang Lake on July 14,2020

Cold wave and snowstorm weather pounding Northeast China in early winter

From November 17 to 23, heavy rain and snow weather emerged in Northeast China. The maximum scale of temperature drop surpassed 8℃. 9 counties and cities like Jilin, and Liaoning broke historical temperature drop scale extremes and many places ushered in “freezing cold” weather conditions.

Distribution image of the largest temperature drop in China from November 17 to 23,2020

Early onset, high frequency, and strong intensity of severe convective weather in 2020

Severe convective weather started earlier, which was characterized by high convection frequency, big differences between northern China and southern China, and strong intensity in some regions in 2020. The first large scale severe convective weather process started one month earlier than that normal years. From March to mid-September, 56 regional severe convective weather processes emerged in China, which exceeded the number compared with the same period of normal year (47 times on average in the recent five years).

Zaozhuang of Shandong province was exposed to severe convective weather and the crops gotten flattened.

Declining number of hazy days in 2020

The number of days of haze in the past 10 years continued to drop off in China. In 2020 (by December 28), the number of days of haze was 24, about 15.7 days shy of the average number in the past decade.

Historical changes of average number of days of haze from the year 2010 to 2020 in China

High temperature and diminished rainfall in South China leading to the continuously meteorological drought condition

In the summer of 2020, the average number of days of high temperature in China was 11.5, which was 2.3 more than the number in normal years. South China experienced the second most number of days of high temperature since 1961. In the meanwhile, rainfall in most portions of South China was less compared with the same period of normal years. High temperature and less rain led to different levels of meteorological drought conditions in South China.

parched Xiangshui Reservoir in Luchuan County in Guangxi on July 18

Frequent rainstorm battering Sichuan Basin in August subjecting some regions to disasters

In the mid-August, heavy rain process plagued Sichuan Basin, with 5 stations in areas like Lushan and Mianzhu witnessing local historical precipitation extremes.


Precipitation distribution map in China from August 11 to 20, 2020

Favorable conditions for flourishing vegetation growth in 2020

From May to September 2020, in most regions of central-eastern China: the precipitation was heavier; the temperature was higher; and the climate conditions were favorable for vegetation growth. Normalized Difference Vegetation Index (NDVI) in China was 0.4609 in the growth season (from May to September),which was 4.9% higher compared with the average number in the recent two decades.

Historical changes of average vegetation index in China, from May to September 2020

Top Ten Global Weather and Climate Events

The succession of El Nino and La Nina adding uncertainties of climatic anomaly

Sea surface temperature (SST) anomaly distribution image in the winter of 2019/2020 (up) and the autumn of 2020 (down) showed that SST was abnormally higher in central and eastern equatorial Pacific in the winter of 2019/2020. Abnormally lower in central and eastern equatorial Pacific in the autumn of 2020.

Covid-19 reducing global GHG emissions while not reversing the trend of climate warmingAccording to United in Science 2020, jointly released by World Meteorological Organization (WMO) and multiple institutions, during peak lockdown in early April 2020, the daily global fossil CO2 emissions dropped by an unprecedented 17% compared to 2019. According to the provisional WMO report on the State of the Global Climate in 2020, the global mean temperature for January to October 2020 was around 1.2°C above the 1850–1900 baseline, used as an approximation of pre-industrial levels. 2020 is very likely to be one of the three warmest years on record globally.


Global surface temperature and SST difference between January-October 2020 and 1981-2010

Heavy rain in many countries of East Africa triggering flooding disasters

From the second half of April to May, abnormally severe heavy rain walloped many places of East Africa, triggering large scale flooding and worsening the impacts on physical health and food security of local people exerted by Covid-19. During the second half of May, rainfall in Kenya, Ethiopia, and Somalia registered 100-200 mm respectively, with some regions exposed to 200 mm precipitation.

Japan experiencing violent plum rain in July

During the first half of July, affected by the frontal surface of the plum rain, central-western Japan was subjected to violent plum rain, triggering off flooding, and landslide. Kochi Prefecture and Nagano County witnessed the heaviest cumulative rainfalls, which surpassed 1400 mm.


Cumulative rainfall distribution in Japan from July 3 to 14, 2020 

Severe tropical cyclone Amphan in Bay of Bengal pelting India and Bangladesh

On May 20, severe cyclonic storm Amphan in Bay of Bengal made landfall with the maximum wind intensity of scale 14 (42m/s, severe typhoon scale). When it strengthened into the strongest scale on the sea, the maximum wind intensity at the center registered scale 17 (58m/s, super typhoon scale). The typhoon resulted in damage of huge quantities of houses and bridges, and power cut or communication outage in some regions.

Image of severe cyclonic storm Amphan captured by FY-4A meteorological satellite

Record–breaking naming of tropical cyclones over the North Atlantic

On November 4, with the generation of the 28th hurricane Eta over the North Atlantic, the naming of tropical cyclones over the North Atlantic in 2020 has tied the maximum record(the year 2005) in history. Afterwards, the 29th tropical storm Theta and the 30th hurricane Iota were generated successively, and the naming of tropical cyclones over the North Atlantic broke the record. Among them, hurricane Iota has become the most severe tropical cyclone over the North Atlantic in 2020 (with the intensity reaching category 5).

Cloud image of hurricane Iota captured by FY-3D meteorological satellite

Lightning strikes in India taking heavy tolls

In Indian state of Bihar, at least 83 people were killed in lightning strikes on June 25. The victims were mainly farmers in the field. It is rare to see the death toll of over 80 people caused by lightning strikes within one day.

High temperature and more rainfall contributing to locust invasion spreading to Africa and Asia, affecting food security in many countries

In December, 2020, Kenya was heavily affected by the worst invasion of locusts in 70 years. Ethiopia and Somalia were subjected to the worst invasion of locusts in 25 years. Locusts have not only raged across countries in East Africa, but also penetrated into countries like Saudi Arabia, Sudan, Yemen, Oman, and Iran during the first half of 2020. Afterwards, locusts traversed the boundary of Pakistan and imposed the most severe locust disaster on the country.

Extreme high temperature in western United States resulting in frequent wildfire outbreaks with unprecedented extent of burned area

From August to October, wildfires triggered by extreme high temperature and strong winds burned in 12 states of western portions of the United States, with California, Washington, and Oregon subject to the gravest fire condition. Wildfires scorched many cities and towns of Oregon, which gave rise to the most severe life and property losses in the history of the State. Since the inception of 2020, California has witnessed over 8000 wildfires, which claimed lives of tens of people, destructed over 8000 buildings, displacing over 50 thousand people, and resulted in accumulated burned area of 16 thousand square kilometers.

Wildfire in western portions of the United States captured by FY-3D meteorological satellite

Extreme high temperature of 38℃ and sea ice extent second lowest in history in the Arctic

From June to August, northern portions of Siberia experienced temperature 2~5℃ higher compared with that in normal years. On June 20, a new record temperature north of the Arctic Circle of 38℃ was observed in the Russian town of Verkhoyansk amid a prolonged Siberian heatwave and increase in wildfire activity. On September 15, 2020, Arctic sea ice reached its annual minimum extent of 3.74 million square kilometers, which was second only to the record-low extent.


Average temperature anomaly distribution in the Arctic Region from June to August, 2020

Comparison of Arctic Sea Ice Extent of all Years 

The annual selection activity of weather and climate events is sponsored by Beijing Climate Centre.(Jan.12)

Editor: Liu Shuqiao