Air Temperature

In the first decade of December, the distribution of decade-averaged air temperature over the territory of Russia was of zonal character. The weather was abnormally cold in the north (with the anomalies down to -5…-7°), but abnormally warm in the central part and in the south (with the anomalies up to +5° in European and to +6…10° in Asian territories). The thermometer readings sometimes dropped below -30° in the Arkhangelsk, Vologda, Kirov and Kostroma Regions, below -40° in the Kostroma Region and the Republic of Komi, and below -60° in the north of Yakutia. At the same time, the record-breaking heat was observed in the Voronezh, Belgorod, Astrakhan and Tyumen Regions, in the Republics of Mari El, Crimea, Bashkiria and Udmurtia, as well as in the Trans-Baikal and Primorye Territories.

In the second decade, the anomalous colds shifted beyond the Urals to the northern and central regions of Siberia, to Yakutia and the Far East. There, frosts reached as low as -40…-45°.
In the third decade, the weather became colder than usual in most of the country already: the anomalies of decade-averaged temperature were -2…-5° in the ETR and -2…-7° in the ATR. The untimely warm weather persisted solely in the Northern Caucasus, partly in the South Federal District, in the south of West Siberia, in Taimyr and its adjacent areas. Conversely, the unprecedented minima of cold were recorded in the Amur Region, and in the Khabarovsk and Primorye Territories, and were not just daily minima, but also monthly ones in some locations.
On the monthly scale, the air temperature in December was sub-normal in the north of the country. The anomalies of monthly-averaged air temperature were -2…-4° in the northern regions of the ETR and in the north of the Urals, Siberia and Far East. To the south of this territory, the temperature was either close to normal, or higher than that.
As for the whole year 2021 in Russia, it was abnormally warm, quite habitually already because all years since 1999 were. However, while the preceding 2020 was record warm in the history of meteorological observations, this year was ranked only in the middle of the second ten warmest years, and was in excess of 2° colder than the winner in the ranking list. The yearly- averaged air temperature all over the Russian Federation excluding the Chukotka Peninsula was above-normal. The highest anomalies reaching +2…3 or more degrees were observed in the Arctic as well as in Yakutia, in the Lower Volga region and in Tyva. This year in the Southern and Northern Caucasian Federal Districts and in the southern regions of the Far Eastern Federal District was among the Top Ten warmest in the history of meteorological observations. The months of record-breaking warmth were August for the entire Russia, June for the ETR and also July in the North-Western Federal District, May in the Volga Federal District, and July as well November in the Far Eastern one.
In East Asia, the average temperature in December was close to normal or above that. In China, the normal values were exceeded by 2-3 and more degrees in the north-west and east. The temperature averaged over the whole country exceeded the normal value by almost 2°, and was the fifth highest in the ranking list since 1891. At the end of the month, frosts down to -40° and below came to the north-eastern regions of China.
In most of South-East Asia, the air temperature was approximately normal.
The situation in South Asia was similar. A new daily temperature maximum was recorded on the first day of December in Bangladesh.
In the Near and Middle East, this December was noticeably warmer than usual. For example, the monthly-averaged temperatures in Iran, in the south of Turkey and in some regions of Saudi Arabia were 2-3 or more degrees higher than normal. The daily temperature maximum was observed in Azerbaijan.
The temperatures in most of North Africa matched their normal values, and exceeded them by 2-3° in some places of the countries to the south of Sahara only.
The weather in Central Asia was unusually warm. The normal monthly averages were exceeded by 2-6° in Kazakhstan and by 2-4° in Turkmenistan, Uzbekistan and Kyrgyzstan.
The averaged temperatures in December calculated across the entire European continent were just slightly above-normal. Yet the temperature anomalies were distributed non-uniformly: the normal values were exceeded by 2-3 or more degrees in the west of Spain, in the UK, in France, Germany, Austria, Switzerland, in the Benelux countries and in the south-east of Romania and Bulgaria, but were not reached by the same 2-3° in the Scandinavian and Baltic countries. Severe frosts with new temperature minima were recorded in Sweden and Estonia at the beginning of the month. The thermometer readings dropped below -43° in Sweden and below -35° in Finland. The air temperature in Tallinn remained below -20° for several days in a row. At the end of the month, abnormal heat came to Europe, with new daily maxima of Year's Eve temperatures observed in the UK, in France, Germany and Spain, and in the Netherlands. In a number of places, the temperature crossed the +20--22° marks sometimes.
In North America, the weather was abnormally warm. Unprecedented heat was observed everywhere from the Gulf of Mexico to Canada. In the USA, the anomalies of monthly-averaged temperature were as high as +2…7° and above. A temperature over +23° was recorded in the state of Iowa in the middle of the month. Eventually, this December became the warmest one in the history of the country. In Alaska, the air warmed up to +19.4°: no such warmth in December has been ever seen there. In the east and north-east of Canada, the normal monthly figures were overridden by 2-6°, and temperature maxima higher than +22° were recorded. But in the western Canada, frosts reached as low as -55° sometimes, and the monthly-averaged temperatures were 2-4° below their normal values.
Unusually warm weather settled in Greenland. The thermometers in the north of the island indicated up to +8.3° even though the temperature in this area is usually not higher than 20° in December. In some regions, the snow cover disappeared right amid the winter.
The yearly-averaged temperature in the Northern Hemisphere was ranked (to an accuracy of 0.1°C) the third to sixth highest along with the ones in 2015, 2017 and 2019. The year 2020 remained the record-holder, with 2016 at the second position. The average air temperature in almost the entire Hemisphere was above-normal in 2021, with the exception of some parts of Alaska, its neighbouring Chukotka, certain regions of India and of the World Ocean where the equatorial zone of the Pacific Ocean was especially remarkable: there, La Niña, a cold episode of the Southern Oscillation, developed in the first half of 2021 and at the end of the year. This year was the warmest in the meteorological chronicle of China and the second warmest in North Africa, and entered the Top Five warmest in the USA and Canada. High anomalies of +3…4° of yearly-averaged temperatures were observed in North America, in the Arctic and the Near East.
In Moscow, December was colder than normal with an anomaly of -0.9°, while the year in overall, warmer than normal by 1.5°.

Sea Surface Temperature

In the Pacific Ocean, La Niña was gaining strength. The area of negative SST anomalies extended noticeably: in the east of the Ocean, to the coast of Mexico in the Northern Hemisphere and to Chile in the Southern Hemisphere. In some locations, negative SST anomalies exceeded 1°. The other vast water area of negative anomalies spread from the north of the USA to the Bering Strait. In contrast, positive SST anomalies of up to +1…2° and above prevailed in the centre of the Ocean and along the Asian coast.
As for the Atlantic Ocean, almost its entire surface in the Northern Hemisphere was occupied by positive SST anomalies. Weak negative anomalies were only observed in the Canary Current along the African coast, and partly off the coasts of Greenland and Scandinavia in the north. At tropical latitudes, the SST anomalies were +1…2°, the same as off the southern coast of Greenland as well as in the Greenland and North Seas. The average SST in the Northern Hemisphere reproduced its maxima previously recorded in 1998 and 2003.
In 2021, the average surface temperature of the World Ocean in the Northern Hemisphere was higher than normal everywhere save for the equatorial latitudes of the Pacific Ocean where La Niña was observed from January to May and from September to the end of the year. In the Pacific Ocean, the yearly-averaged SST at temperate latitudes and in the west of tropical ones exceeded the normal values by 1.0-1.5°. The same picture was observed off the Atlantic coast of North America from Florida to Greenland.

In the ETR, the precipitation amounts in December were normal or sometimes increased in most constituent entities of the Federation, with the exception of the Northern Caucasian Federal District or certain areas of the Volga region and Kaliningrad Region where they turned out to be less than normal. At the beginning of the month, heavy rains took place in Central Russia, and at the end of the month, rains with sleet descended upon the southern regions. Up to 35-45 mm of atmospheric moisture per day could accumulate in the Rostov Region, in the Krasnodar Territory and in Kalmykia. New daily precipitation maxima were set in some places. The amounts of snow were so large that the height of freshly fallen snow reached 30 cm in some areas. The water level in the rivers rose significantly and reached the record-breaking values. A number of human settlements were flooded.
A lot of precipitation came to the Urals and to the southern regions of West Siberia: there, the normal monthly totals were exceeded by 1.5-2.0 or more times, e.g., by almost three times in the Novosibirsk Region. On the other hand, precipitation in the south-east of Siberia was scarce: less than a quarter of the normal quantity in Khakassia, for example. In the Far East, precipitation was abundant in the Trans-Baikal, in Kolyma and in Kamchatka, exceeding two normal monthly amounts in some locations. On the contrary, the total figures were very low in Primorye, especially in its southern regions. In the Magadan Region, new daily precipitation maxima were established at some points.
In yearly terms, the precipitation amounts were normal in most of Russia, and were in lack solely in the south-east of the Volga region, in the south of the Urals and in certain areas of the Far East.
Massive snowfalls passed across the south-west of Japan; in some places, they brought more than 70 cm of snow in a single day or more than 1.5 m in three days. These snowfalls were the strongest in the meteorological annals of the country, with the normal monthly precipitation amounts exceeded by two or more times. In the rest of Japan, the normal precipitation figures were reached. In China, the precipitation quantities were normal or larger than normal (by 2-3 times in places) to the south of the Yangtze river and in the north-east of the country. In the rest of China, the weather was mostly dry, with no precipitation at all in some regions of the central part. As regards the whole year, the precipitation totals were close to normal or above-normal in China and Mongolia, approximately normal in Japan, and sub-normal in Korea.
In the north of Thailand, rains caused floods at the beginning of the month but became rare later on. Since the middle of the month, intensive rains poured in Malaysia, bringing up to the normal monthly rainwater amount per day in some places. This resulted in a flood considered as the most powerful in the past 100 years by the local experts. Typhoon Rai brought rains, landslides and floods to the Philippines.
Quite unexpectedly for a dry season, a lot of rains went to the north of India in amounts up to two normal monthly totals in some places; however, almost no precipitation was observed in the south of the country and in neighbouring Pakistan alike.
The weather in the Near and Middle East was mostly dry. Many meteorological stations reported zero in the "monthly precipitation total" column. Nonetheless, occasional rains were very heavy. The record-breaking precipitation was observed in Israel where the normal monthly amount was reached in two days, and the streets of several towns were flooded. Snow fell on the Mount Hermon for three days in succession. Rains took place in Syria and Iraq as well, and caused floods in these countries.
The weather in South Africa was also dry. This month, a part of the Sahel region was affected by the worst drought in recent years. No rains were observed in some areas for more than a year. But in the south of Sudan, rains caused the strongest flooding in the last sixty years.
Either normal or increased rainfall amounts were recorded in Kazakhstan, and in the Aral Sea area in north of Uzbekistan. Heavy rains in the west of Kazakhstan resulted in new maxima of daily precipitation. To the south of this region, almost no precipitation was observed in December. In total, yearly precipitation figures in Central Asia were noticeably lower than normal.
In Europe, the weather was dry in the Scandinavian countries, in most of the Iberian Peninsula, in the north of Italy, in Switzerland, and in the south-east of France. The precipitation amounts in the rest of the continent were normal, or larger than normal: by 1.5-2.0 times larger in the west and south-west of France, in Ireland, in parts of Central Europe and in the centre of Italy, but most impressively, by 2-3 times in the Balkans. In the first half of the month, pelting rains often poured in the north of Italy and the south-west of France where up to 200 mm of rainwater would fall for several days. Snow accumulated in the mountains before was rapidly melting, and assisted rainwater flows in ramping up the levels of the rivers and in flooding; in the north of Spain, the floods were most severe for the past twenty years. In Ireland, abundant rainfalls bringing up to 85 mm of precipitation per day in places caused great floods never seen in the country since fifties of the previous century. In Romania, severe floods also took place due to enduring and incessant rains.
In the east of the USA, the normal precipitation figures were gained in general, with the exception of the Atlantic coast where these figures were low. The precipitation amounts were normal in the centre of the country, and considerably higher than normal in its north and west (by 2-3 or more times higher in some locations). Torrential rains and ample snowfalls hit California. In Sierra Nevada, the snow cover height in the mountains reached three metres, and this December became the snowiest in the history the state. In Nevada, Arizona and Oregon, new maxima of daily precipitation totals were established. The normal monthly amounts were accumulated in just a few days in some places.
In Canada, precipitation was abundant in the central part of the country, approximately normal in the east, and significantly less than normal in the west. In Mexico, the weather was dry almost everywhere apart from the northern regions of the country where up to two monthly precipitation amounts, or even more, fell along the boundary with the United States.
As for the year 2021 in total, precipitation was normal in most of North America. The exceptions were the US states of California and Arizona, as well as the south-eastern territories of Canada where a shortage of precipitation was observed.
In Moscow, 67 mm of precipitation fell in December; this is 120% of the normal amount. The yearly figure for 2021 was 844 mm: this is also close to normal.