The abnormally cold weather which settled in the second half of November in most of the ETR became even colder in the first decade of December. Frosts in the Kursk, Belgorod, Yaroslavl, Ivanovo, Kostroma, Samara, Volgograd and Astrakhan Regions and in the Republic of Kalmykia reached 20…-25°. Freezing down to -3° was observed on the coasts of Crimea and of the Krasnodar Territory. In the outcome, the decade-averaged temperature in the south and in the Volga Region turned out to be 2-6° lower than normal. At the same time, the weather was abnormally warm in the Russian North where the normal values of decade averages were exceeded by 5-10°. In the second decade, warmth extended its boundaries within the ETR. The weather became 2-3° warmer than usual in the central region, and the temperatures sometimes reached new daily maxima in the south (in Anapa and Tuapse). The Volga Region was the only one where it was still noticeably colder than usual. Yet, the warmth came even there in the third decade. The average temperature was above its normal value everywhere apart from the Lower Volga: 1-2 degrees above in the Volga Region, and 4-5 or more degrees above it in the south. All-time highs of air temperatures were recorded in the Crimea and Caucasus, and the thermometer readings were close to the +20° mark sometimes.

Over the whole duration of the month, the temperature contrasts were even more apparent in Siberia where the average temperature in the first decade was 8-11 or more degrees higher than normal, but the unprecedented colds came in the second and third decades. Frosts below 50° invaded a huge territory in the east of the country and reached -54…-56° in Yakutia and Evenkiya. Colds that had never been observed before were recorded in Western Siberia. In the third decade, the decade-averaged temperatures were lower than the normal values by 10-13 or more degrees. The monthly temperature patterns in the Far East resembled those in Siberia: warm weather in the first decade (anomalies of +5…8°) followed by cold weather in the second and third ones (anomalies reaching -6°) everywhere save for the north-eastern region where warmth prevailed during the whole month. Such temperature distribution in December resulted in the monthly-averaged air temperatures 1-3° higher than normal in most of the ETR excluding the Volga Region where this temperature was by about the same value lower than normal, just as in the Urals and in Western Siberia. In most of the Far East (Yakutia, Trans-Baikal, Kolyma and Chukotka), warmth prevailed on the monthly average, and the only areas where the weather was somewhat colder than usual were Primorye, Sakhalin and partly the Khabarovsk Territory. Neither in any federal district, nor in Russia as a whole, did the monthly-averaged temperature reach the record-breaking values in December.

The same can not be said about the whole year. Its average annual background was striking. In each federal district other than North-Caucasus, an absolute maximum of the yearly-averaged temperature was reached for the first time in the entire 130-year history of meteorological observations. (This temperature in the North-Caucasus Federal District was awarded rank 3 among the highest values). The previous records set in the Ural and Siberian Federal Districts were exceeded by 1.5° all at once. No surprise that this year became the warmest in history both in entire Russia, and in its European and Asian parts separately. Recall that February, April, May, September and November were the warmest in the annual course, while January, March, June, July and October entered the Top Five of warmest ones.

The yearly-averaged air temperature was higher than normal everywhere in Russia, by 2° or more as a rule, and by 3° in the European or 3.5° in the Asian territory on the average. The largest positive anomalies (in excess of 5-7°) were measured in the north of the Urals, in Siberia and in Yakutia, and the normal yearly-averaged temperature was most exceeded in Taimyr (by more than +7°). 14 out of 15 warmest years in Russia belong to the 21st century, with the sole year 1995 left at the end of the 20th one.

December in most of East Asia was colder than usual. In some locations, the monthly-averaged air temperature was 2-4° lower than normal in China, Korea and Japan, and even lower than that in Mongolia. The lowest air temperature (-24.8°) since December 1978 was recorded in Beijing. The temperatures were slightly higher than normal in the north-east and south-west of China in the provinces of Heilongjiang, Jirin, Liaoning and Yunnan, as well as in certain regions of Japan.

The temperature was about normal in South-East Asia and in India.

Cold weather in the Middle East (with the monthly-averaged temperature 1-2° below the normal value in Iran) contrasted with the abnormal warmth in the Near East where the monthly-averaged anomalies of temperature exceeded +2°.

The same anomalies were observed in Egypt and Sudan in the north-east of Africa as well as in the countries to the south of Sahara. The monthly-averaged air temperature in the rest of North Africa was either close to normal or slightly higher than that. As a result, December 2020 became the third warmest in the history of meteorological observations in the continent.

Cold weather prevailed in the countries of Central Asia in December. Severe frosts down to -30° in places were observed in Kazakhstan and Central Asia. New minima of temperature were recorded in the west of Kazakhstan. The monthly-averaged air temperature throughout the region was 2-6° below the normal value.

The weather in the European continent was abnormally warm this month. The anomalies in the west of Spain and in the UK were +1.0-1.5°, and grew higher and higher in the eastward and northward directions. New events of unprecedented warmth were reported in France, Germany, Austria, Belarus and Ukraine. The anomalies of monthly-averaged temperature were +2..3° over a large part of the continent, and +5…8° or more in the Scandinavian countries from its north.

This December was abnormally warm in most of the North American continent, especially in Canada where the monthly-averaged air temperature was two or more degrees higher than normal almost in the entire country: by 4-6° in the province of Saskatchewan from the south, or by 6-10° or more in the Arctic region from the north. As a result, the average December temperature after its averaging over the entire territory of the country occupied the position right after the Top Five of highest values in the ranked list. In the USA, this month was also much warmer than usual everywhere, possibly excluding the south-east of the country (the states of Florida and Georgia). The weather was 2-4° warmer than normal in most of country, and 4-6° warmer to the west of the Great Lakes in the north.

To an accuracy of 0.1°C, the yearly-averaged air temperature in the Northern Hemisphere was the highest in the history of regular meteorological observations on the planet, i.e., since 1891. Even though the anomalies over most of this vast area were lower compared to those in Russia, they were still positive (+2…3° or higher) almost throughout its entire continental territory. The year 2020 became the warmest in the history of Europe where new maxima of yearly-averaged temperature were recorded for the third year in succession. In China, the record-breaking achievement of 2007 was reproduced, and in the Arctic, this year was the second warmest in the meteorological annals of the region: there, the average temperature was just slightly below the all-time maximum of 2016. In the United States and in North Africa, the year 2020 entered the Top Five of warmest years. According to Meteo France, this year was the warmest for 120 years of observations in France; a similar message came from Kiev.

In Moscow, the average temperature in December was -4.4°, and its anomaly was +1.7°. This year was the warmest in the meteorological chronicle of the capital. Its temperature was +8.0°: this is 0.2° higher than the previous record-breaking value set in 2019 and 3.0° higher than the normal value.

In December 2018, the average surface temperature of the Pacific Ocean in the Northern Hemisphere reached its all-time maximum when El Niño was responsible for abnormally warm water at the equator. In December 2020, this maximum was achieved again even though El Niño was now replaced by increasingly strengthening La Niña featuring abnormally cold water at the equatorial belt. This was possible owing to the extremely warm water in the subtropics: there, the SST anomalies were +1..2° or higher. As for the whole year 2020, the annual average SST of the Pacific Ocean reached the maximum value.

In the Atlantic Ocean, the average SST anomaly remained at the previous level, i.e., was close to 0.5°. Large positive anomalies were observed in the west of the Ocean, and negative ones, in the east. The SST was noticeably higher than its normal value in the marginal seas of Europe as well as in the Barents and Kara Seas in the north.

In the ETR, precipitation in December was scarce everywhere save for the North-West and North-Caucasus Federal Districts. In the former one, the normal monthly precipitation amount was achieved in most constituent subjects of the Federation, and in the latter, this amount was significantly exceeded (by 1.5-2.0 times) in the Republics of Dagestan and Kabardino-Balkaria, and in the Chechen Republic. The rest of the ETR received about half the normal monthly precipitation amount or less. Still, occasional heavy rains and snowfalls did occur. For example, the rains in the Crimea introduced new daily precipitation maxima at the beginning of the second decade. In the middle of the decade, rains and snowfalls invaded the Lower Volga and the south of Russia. In the Saratov and Rostov Regions, 15-24 mm of snow fell overnight in some places. A snow cover up to 15 cm deep was formed. At the end of the decade, heavy snowfall hit the Black Sea coast of the Caucasus where the depth of the snow cover reached 20-30 cm in certain locations. At the beginning of the third decade, heavy precipitation swept across the North Caucasus. New daily precipitation maxima were recorded in Dagestan and Chechnya.

Precipitation was normal in the north of the Urals, and much less than that in the south (in the Chelyabinsk and Kurgan Regions). Beyond the Urals, the monthly precipitation totals were distributed non-uniformly in Siberia and in the Far East: e.g., they were normal in most constituent subjects of the Federation in the Siberian Federal District, but very small in the Republic of Khakassia and the Irkutsk Region. In the Far East, the precipitation amounts were normal in Yakutia, in the Magadan Region and in Kamchatka, and decreased in Primorye, in the Amur Region, the Khabarovsk Territory, Chukotka, and the Trans-Baikal Territory (although they were almost two times higher than normal in the neighbouring Republic of Buryatia). Much snow came to Sakhalin and Kuril Islands, resulting in new daily precipitation maxima in places.

Precipitation was scarce in Mongolia, Korea and north-east China, as well as in Tibet. Precipitation in the form of either rain or snow was only observed in the central regions of China and in Japan. In the middle of the month, the latter was hit by record-breaking snowfalls that created snow banks up to two metres high just in a few days in some places. Rains and creeping snow caused landslides. The normal monthly precipitation figures were exceeded by 1.5-2.5 times in some locations of Japan and Central China.

In South-East Asia, downpours mostly occurred in the south regions of Thailand and Indonesia, and in the Philippines. They caused massive floods that deluged hundreds of villages and inundated agricultural lands. Landslides took place at the same time. On the island of Java, 130-180 mm of rainwater fell for several days: there, the normal precipitation amounts were exceeded by 2-3 times or more.

In the Hindustan Peninsula, rains were observed in the south only, while the rest of India and Pakistan received scanty precipitation.

Iran suffered from heavy rains. More than 150 mm of atmospheric moisture fell in a few hours in some areas of the country. In the north of Iran, heavy snowfalls occurred at the end of the month and caused fatalities among the population. Yet in overall, the monthly precipitation amounts in most of Iran were normal. In the rest of the Middle East, precipitation was scarce, with the exception of Turkey and the northern regions of Saudi Arabia where its monthly totals were either normal or increased. In parts of Turkey, rains caused floods that brought up to 40-70 mm of precipitation per day here and there.

The weather in North Africa was dry. Rains, or snowfalls in some places, were observed on the Mediterranean coast of Algeria and Tunisia only.

The precipitation amounts in the countries of Central Asia were sub-normal. A heavy snowfall took place in Aktobe (Kazakhstan): on that day, 14 mm of precipitation fell in the form of snow, creating a new daily maximum for this location.

In Europe, showers and snowfalls were rife in December. At the beginning of the month, they hit Italy, Austria and the Balkan countries. In some regions of Italy, rains were heaviest in the past 70 years. In Venice, they caused flooding such that the Doge's Palace and the Cathedral of San Marco, the masterpieces of architecture, were drowned again. In Rome, 40 mm of rain fell for a single day. Snow that was observed the Austrian Alps brought 250 mm of precipitation in three days. In this area, snow banks reached three metres in height. Snow was also falling in Serbia, Romania and Cyprus. Rains were pouring in Croatia, Montenegro, Albania, Slovenia and Moldova, producing up to 100 mm of rainwater per day. At the end of December, snows returned to the north of Italy and covered the ground with a blanket 15-20 cm thick in Lombardy, Piedmont, Veneto and Liguria. Heavy rains in the UK and in Iceland caused floods and landslides. Considering the monthly figures, the normal values in many areas in the west, south and north of the continent were exceeded by 1.5-2.0 times or more. The precipitation quantities were normal or decreased in the east of the continent only.

Heavy snowfalls took place along the east coast of the USA in mid-December. The height of fresh snow exceeded 1.5 metres in the states of New York, Pennsylvania, Virginia and New Jersey. Due to heavy snowfalls, a state of emergency was declared in the state of Ohio. The normal precipitation rates in the east of the country and in Texas were exceeded by 1.5-2.0 or more times at some locations. On the contrary, the weather was dry in the west; there, the monthly precipitation totals were much less than usual. The situation was about the same in Canada: dry weather in the west, but normal or above-normal precipitation in the east. The normal amounts were exceeded by 2-3 times in the Arctic region. In Mexico, the weather was mostly dry. In Columbia, a landslide that was triggered by torrential rains in the north-west of the country claimed the lives of people.

In annual terms, the precipitation rates were normal or slightly increased over most of the Northern Hemisphere. They were noticeably higher than normal in India and individual countries of the Sahel region in Africa, and noticeably lower than that in the south-west of the US, in the north of Mexico, as well as in the countries of North Africa and Central Asia. In Russia, precipitation was lacking in the south regions of the ETR.

In Moscow, 30 mm of precipitation, or 53% of the normal quantity, fell in December, and 888 mm, or 128% of the normal quantity, fell for the whole year 2020.