The abnormally warm weather which reigned in the ETR during the first month of autumn smoothly migrated to October. The anomalies of decade-averaged temperature at the beginning of the month grew even higher: up to +5-7°. New daily temperature maxima were recorded both in the north (Nizhny Novgorod and Vyborg) and in the south (the Crimea and the Black Sea coast of Caucasus). In the second decade, the weather remained relatively warm in the central regions, and became still warmer in the south and south-east. The thermometer readings in the Crimea and the Black Sea coast approached the 30-degree mark and crossed it in some places. But at the end of the decade, autumn disclosed itself at last and brought first night frosts to the Moscow, Black Earth, Volgograd and Rostov Regions. Yet, the weather in the ETR, remarkably in its south, was abnormally warm until the end of the month. As a result, October 2020 in Central Russia became the warmest for the entire 130-year history of meteorological observations. The previous long-lived achievement of 1896 was exceeded by more than half a degree right away. In the South Federal District, this October was the third warmest; as for the ETR as a whole, the monthly-averaged temperature reached an absolute maximum exceeding the previous one set in 1923 and later repeated in 2008.

In the Urals and to the east of them, the month was also very warm. The average air temperature in the second decade was 5-7° higher than normal in certain areas, most noticeably in the north-east where new highs were recorded for several days in succession. And eventually, this October in the northern regions of the Far East turned out to be the warmest one in the meteorological chronicle. As for the south of Siberia, cool weather with sub-normal temperatures persisted in the first decade and furnished the temperature anomalies of -3…-4°.

In the Russian Arctic, extreme temperatures were measured on all days of the month. The record-breaking heat was observed both on the Arctic islands and on the coasts of Yakutia and Chukotka. There, the anomalies of decade-averaged temperatures reached +10-11 and more degrees in the second and third decades.

Regarding Russia in general, the average temperature of October 2020 shared the third line in the list of highest values with October 2008, and was lower (by more than a degree) than the unsurpassed maxima of 2018 and 1967 only. All over the country, the month was warmer than normal: by 2° and more as a rule, or by 3-4° and more in the centre of the ETR. But the largest anomalies of monthly-averaged temperature took place in the north-east of Russia and in the Arctic where they exceeded +4…10°.

In the east of Asia (China, Mongolia, Korea and Japan), the monthly-averaged air temperature was close to normal, and either slightly above it (by 1-2°) in some places (in Japan and in the north-eastern and north-western regions of China), or by the same value below in some other ones (in the south of the Korean Peninsula).

The picture was roughly the same in the South-East Asia and on the Hindustan Peninsula.

The weather in the Middle East was hot: the air temperature could rise to +30° and above, and the monthly averages exceeded their normal values by 2-4°. In Syria, Israel and the east of Turkey, hot and dry weather led to numerous fires that invaded large territories. The authorities were forced to evacuate tens of thousands of people.

In most of Kazakhstan, the monthly-averaged temperature was above-normal, with the anomalies increasing in the northern direction (up to +2-3°). On the other hand, October was cold in most Central Asian countries. In Uzbekistan and Kyrgyzstan, the thermometer readings dropped to -4…-5° at the beginning of the month to result in new temperature minima. Yet in overall, the temperature in October was generally close to normal in this region, with the exception of central areas where it was 1-2° below the normal value.

North Africa was captured by hot weather: the monthly-averaged temperature was higher than normal almost everywhere, especially in the north of the continent (with the anomalies of +2-3°). In Libya, the heat resulted in serious fires. In the midst of such heat, the weather was surprisingly cold in the north of Algeria where the monthly-averaged temperature was two or more degrees below the normal value.

In Europe, the temperature background in October was abnormally warm in the east, south-east and north of the continent, and abnormally cold in the west. In Poland, in the Baltic countries, in Belarus, Ukraine, Romania, Moldova and Greece, the monthly-averaged temperature was 2-3 or more degrees higher than normal, while in Italy, France and Spain, this temperature was lower by the same amount. The Meteorological Service of Spain reported that this October was the coldest one in the country for the past ten years. At the beginning of the month, the events of record-breaking heat were logged in the Scandinavian countries, while at its end, 30-degree temperatures could still occur in Cyprus in the east of the Mediterranean.

In the USA, October was cooler than usual, albeit that in the central regions only: there, the monthly-averaged temperatures were 2-4° below normal. In the states west of the Great Lakes from Wisconsin and Milwaukee to both Dakotas, October 2020 entered the Top Ten of coldest in the entire history of meteorological observations in the country. At the end of the month, colds reached Texas where the temperature fell to -15° in Denver. Even more severe frosts, of -25° and below in places, were recorded in Nebraska, Wyoming, Idaho and Utah. On the contrary, the weather on both coasts was much warmer than usual. In California, this October became the warmest in the history of the state. In Arizona and Nevada, the monthly-average temperature was among the first ten of highest in the meteorological chronicle. The same was true for the east coast, from Florida to Virginia. In Phoenix, Arizona, air temperatures above +37°C were recorded on 144 days this year: this is the highest figure since 1896.

Cool weather in the south of Canada was in contrast with the abnormally warm one in the north of the country, especially in the Arctic zone where the monthly-averaged temperature exceeded its normal value by 2-6° or more.

High temperatures everywhere in the Arctic made October 2020 the second warmest in the history of this region, cooler than October 2016 only.

Cold weather in North America, western Europe and South Asia in part, as well as the developing La Niña, prevented the monthly-averaged temperature in October from reaching the all-time highest value in the Northern Hemisphere. This temperature was ranked second to fourth highest in the 130-year series of regular meteorological observations on the planet.

In Moscow, the monthly-averaged temperature in this October was +9.2° implying the anomaly of +4.1°. This was the warmest October in the metrological chronicle of the capital.

Ocean surface temperature

The most important effect due to the surface temperature of the Pacific Ocean in the Northern Hemisphere is the development of La Niña. Negative SST anomalies were observed in the equatorial zone ranging from 150° E to the coast of the American continent, and from 170° W to 105° W where they exceeded 1° and reached 1.5° or more. The area occupied by negative anomalies also covered sub-equatorial latitudes up to 5°N and further to the north. This La Niña is expected to be the most powerful for the last ten years. Calculations show that its peak will take place in the first quarter of 2021. Subtropical and temperate latitudes of the Ocean in October were dominated by large positive SST anomalies in excess of +2° and included a very small area of weak negative anomalies. As a result, the average SST of the Pacific in the Northern Hemisphere reached an absolute maximum even in the presence of La Niña.

In the Atlantic Ocean, most of the water area was also occupied by positive anomalies. Though, they were not as large as in the Pacific Ocean, and could be considered high (i.e., above 1-2°) off the US coast only. The same anomalies were observed in the Arctic along the Northern Sea Route.

As in September, the major amounts of precipitation in Russia went to Siberia and the Far East. In the ETR, their monthly-averaged figures were close to or less than normal. Precipitation was most scarce in the southern regions: less than a quarter of the normal monthly amount in a number of constituent territories (in the Astrakhan Region and the republics of Dagestan, North Ossetia, Chechnya, Ingushetia and Kabardino-Balkaria). Summer draughts in the south of Russia survived until the beginning of autumn; yet, occasional heavy rains did occur. For example, such rains poured in the Crimea in the first decade, bringing about half the normal monthly rainwater amount per day in some places. By the end of the month, a snow cover up to 15 cm in height was formed almost all over the North-West Federal District. Snowfalls took place in Bashkiria, the Perm Territory and the Kirov Region as well.

Precipitation was close to normal in the Urals and to the east of them, with the only exceptions of Taimyr, Evenkiya, the Amur region and the south of the Khabarovsk Territory where the normal values were significantly exceeded. Trans-Baikal and the south of the Far East were flooded with heavy rains at the beginning of October already; there, the daily precipitation exceeded 40 mm in places. In Chita, a new daily maximum of rainwater was recorded, while in Blagoveshchensk, the monthly normal amount fell in just four days. Heavy snowfalls came in the second decade to create a snow cover up to 20 cm and more in height throughout Central Siberia and in Altai. At the end of the month, record-breaking precipitation hit the southern regions of the Khabarovsk Territory, Sakhalin and the Amur Region.

Precipitation was abundant in Mongolia and North-Eastern China in the areas adjacent to the Russian Far East. There, the normal amounts were exceeded by two or more times in places. In Heilongjiang province, a snowfall heaviest for the past ten years produced a snow cover exceeding 20 cm in height. In the centre and the south-west of China, the precipitation amounts were normal or increased. Sometimes, precipitation was so strong that it caused landslides, e.g. in the province of Sichuan. First of all, the latter concerned Inner Mongolia and the entire territory from the province of Qinghai and to the west of it. In Japan, the precipitation amounts were normal, and in Korea, decreased.

A lot of rains poured in the countries of South-East Asia. In Vietnam and Cambodia, they led to floods leaving dozens of people dead and forcing tens of thousands to leave their places of permanent residence. The Meteorological Service of Vietnam reported that a number of rivers reached their highest levels in twenty years, and the country has suffered the worst floods over the last years. In Cambodia, more than 370 thousand hectares of agricultural land went under water. The normal monthly precipitation amounts in these countries were exceeded by 2-4 or more times. The most severe flooding caused by heavy rains took place on the island of Java in Indonesia at the end of October. More than 100 mm of rainwater per day fell there in places.

Torrential rains hit the central regions of India and led to floods that washed out agricultural crops. New highest precipitation amounts were recorded. For example, the daily precipitation in the city of Hyderabad amounted to 320 mm which is four times the normal monthly value. Similar records were set in other settlements. Bangladesh was also hit by heavy rains. But in Pakistan, the precipitation amounts were close to zero.

Similarly, precipitation was almost entirely lacking in Central Asia. Snow fell in the north of Kazakhstan.

No precipitation was present in the Near East. Heavy rains causing landslides were observed in Georgia only.

Northern Africa received virtually no rains, but the countries to the south of the Sahara got them in large numbers: there, the normal precipitation amounts were exceeded by 2-3 times in places. In Congo, rivers overflowed their banks and flooded crops. Floods in the north of Nigeria were the most devastating for the last 30 years – water destroyed a significant part of the harvest, and the fatalities were reported.

The European countries were repeatedly poured with rains during the month. The precipitation amounts were large everywhere from the Atlantic Ocean to Belarus and Ukraine, and their normal total monthly figures on a large part of the continent where exceeded by 2-3 or more times. In some places, up to 100 mm of atmospheric moisture accumulated per day. This created floods that specifically affected Slovenia, northern Italy, southern France, Portugal and Lithuania. In the middle of the month, snow fell in a number of European countries including Slovenia, Romania, Czech Republic, Slovakia and Poland. At the same time, a downpour totalling in daily precipitation twice the normal monthly amount took place in Crete. The southern areas of Italy and Spain were the only ones where precipitation was scarce in October.

The monthly precipitation totals in the USA excluding its western states were either normal or increased, up to 200-300% in some places. Powerful snowfalls occurred in the central part of the country, especially in the north of it. They were observed earlier than ever in the state of Montana. Likewise, snow covered North and South Dakota, Iowa and Minnesota. In some places, the snow cover was as high as 25 cm. In the west, the weather was still dry and hot in California; this contributed to the development of wildfires. This year, they covered the record-breaking area spreading to 16 thousand square metres of the territory of the state. This October was the second driest in the history of California.

Almost no rains fell in Mexico. In certain countries of Central America, in Jamaica and Cuba, heavy rains causing floods have occurred. In Canada, the precipitation amounts were normal except for the northern regions where they were scanty.

In Moscow, the monthly precipitation amounted to 54 mm; this is 91% of the normal value.