The air temperature during all December was close to normal in the European territory of Russia (ETR) excluding its North. Of course, the weather was sometimes colder for several days only to become warmer after an inflow of warm air. As a result, the monthly-averaged air temperatures in the ETR were almost normal albeit that accompanied by weak positive anomalies. And the North, namely, the Murmansk and Arkhangelsk regions as well as the Komi and Karelia republics, was the only exception where the monthly-averaged air temperatures exceeded their normal values by 2-6° or more, with the peak daily temperatures recorded therein.
Siberia rendered an entirely different picture where the cold in the first and third decades contrasted with the anomalous warmth in the second decade, the anomalies of decade-averaged temperatures being as low as -10…-12° in cold periods and as high as the same values negated in warm ones. Moreover, the substantial warmth and the equally strong cold were alternating at a surprisingly high rate from time to time. For example, the daily maximum of air temperatures recorded in Turukhansk in the end of the second decade dropped down in a matter of few days to the daily minimum in the third decade. The coldest temperatures were -40° or below.
The air temperatures in Yakutia were even lower: below -50°, though their monthly-averaged values in the Republic of Sakha were somewhat higher than usual. These values in all territories of the Far Eastern Federal district other than its northern-most East lands were above normal. The only overly cold region was Chukotka where the monthly-averaged temperature was 2-6° below the normal value.
The average December temperature in the country as a whole was close to normal, with its anomaly less than one degree.
The year 2018 in Russia entered the Top Ten of the warmest years in the whole history of regular meteorological observations in this country since 1891. The average temperature was just some half degree lower compared to the warmest 2017. Nine out of ten warmest years were in the 21st century and one, in the 20th, viz., in 1995. The yearly average temperature in 2018 was higher than expected in most parts of Russia: 1-2° higher in the European part and 2-4° higher in Asia. Chukotka and arctic islands in the Barents and Cara seas experienced anomalies about 4° or higher. Weak negative anomalies (less than 1°) were recorded in certain parts of the South Urals, in the Omsk and Novosibirsk regions, and in the Altai Territory.
The last year is in the Top Ten of the warmest years in the North-West, South or North Caucasian and Far Eastern Federal districts. In particular, it is the second and third warmest year in the North of the Far East and the North Caucasus, respectively, as recorded in the metrological chronicles for these regions.
In neither Federal district did the monthly-averaged air temperature ever reach its absolute minimum or anything close to it, but the absolute maxima of this temperature were recorded thrice: in the Siberian Federal district (in June and October) and the Far Eastern Federal district (in October as well). October 2018 was warmest in the Russian meteorological chronicles. Monthly averages approaching the maximum values were recorded in different months of the year in all Federal districts: July and September in the North-West district; May and September in the Central district; May and July in the Southern district; May, June and July in the North-Caucasus district, July and September in the Volga district; September and October in the Urals district; June, August and October in the Siberian district; February, April, June, September and October in the North of the Far-East district and May and October in its South. Regarding Russia as a whole, its monthly-averaged air temperatures were included three times in the Top Ten: in June, August and September, not counting the extremely warm October.
In most parts of Eastern Asia, the average air temperatures in December were basically normal. Certain negative deviations (as large as by 2-3° in some places) were only observed in Mongolia, and positive ones, in South China and in Japan. In the beginning of winter, the thermometer readings in Japan's Honshu Island rose above +25°. For the last time, this was observed as far back as in the XIX century.
It was substantially warmer in South-East Asia where the monthly averages exceeded the normal values by 2-3° or above.
In India, relatively warm weather in the South made up for relatively cold weather in the North to result in approximately normal monthly averages.
Abnormally warm weather prevailed throughout the Middle and Near East. The air temperature in December increased by 1-3° above normal all the way from the Eastern Mediterranean to Iran and Arabia.
The southern regions of Central Asia also enjoyed warm weather: the temperature in Turkmenistan, Uzbekistan and Afghanistan was above normal by 1-2° or more. But in the northern regions, cold weather dominated in Kazakhstan, and the average temperature in December was below normal by the same amounts.
In North Africa, the air temperature was roughly normal. It was somewhat higher in Morocco and in the North of Algeria, and lower in Niger and in the South of Algeria.
In most parts of Europe, abnormally warm weather persisted, especially in the beginning of winter. In Western Europe (Spain) and Central Europe (Slovakia), new temperature maxima were recorded. The temperatures in Valencia exceeded +25°. On the average, the air heated to 2-3° above the December rating in the regions from the Atlantic to Poland and Scandinavia. And yet, winter was still clearly perceivable in Balkans and Greece: the monthly-averaged temperature was below normal there, and new daily minima were recorded in some places.
All over Canada, very warm weather settled in December. The monthly-averaged air temperatures exceeded the normal value by 2-4° in the East of the country and by 2-6° or more in its West. Newfoundland was the only place where the weather was slightly colder than usual. The anomaly of monthly-averaged temperatures throughout the whole country exceeded the normal value by 4°. This anomaly was twice as weak in the USA, the southern neighbour of Canada, amounting to about +2°. Whereas the air temperature averages in all USA territories were higher than normal, this rise was most noticeable in the centre and in the East of the country where the anomalies exceeded +2°.
In overall, the anomaly of average air temperature in the Northern Hemisphere was +0.9° in 2018 (to an accuracy of 0.1°). The average temperature calculated to this accuracy has been assigned rank 4 of the highest values obtained for the whole history of regular meteorological observations on the planet, i.e., since 1891. Year 2016 remained the hottest one demonstrating a temperature rise by 0.2° higher.
Large positive anomalies (in excess of +3-4°) took place in the polar region, most essentially in the Eastern Arctic sector. They exceeded +2° in the Russian North and East, in the Near East, Central and Eastern Europe, East China, North of Mexico, and along the Gulf Stream in the Atlantic Ocean. In Europe, the years 2018 and 2014 were the warmest years in the history of meteorological observations.
In Moscow, the average December temperature was -5.6° and the anomaly was +0.6°. The year 2018 will be marked in the capital's history as one of the warmest years in the metrological chronicles. Its average temperature bottoms the Top Ten of the most highly-ranked values. The record of warmth in 2015 remains unbeaten.

The most remarkable phenomenon in the last month of 2018 was a new El Nino that appeared at equatorial latitudes in the East of the Pacific Ocean. In the Western Hemisphere, the anomalies of ocean surface temperature exceeded 1° for a considerable part of equatorial water areas. In the Northern Hemisphere, the average surface temperature of the Pacific in December regained its absolute maximum observed in 1995. Apart from equatorial latitudes, large positive anomalies took place in the East and West of the Ocean along the North-American and Asian mainlands.
In contrast to this, the average surface temperature of the Atlantic Ocean in the Northern Hemisphere was markedly below normal. A similar situation was last observed more than a quarter of a century ago. Water was very cold in tropical and middle latitudes of the Ocean.
The ocean surface temperature was still abnormally high in the Arctic Basin.
The yearly-averaged surface temperature in most parts of the World Ocean was nearly normal in the Northern Hemisphere. In the Atlantic Ocean, it was noticeably above normal in subtropical latitudes to the East from the North America (with the anomalies along the coast exceeding +1°). In the Pacific Ocean, a similar picture was observed for the whole year in the central part of the Ocean.
The annual anomalies of ocean surface temperature in arctic seas (the Barents, Cara, Chukchee and Bering Seas) exceeded the normal values by 1° and above.
As reported by WMO, the heat content of oceans for each three-month calendar period in 2018 was either the highest or next to the highest for the whole history of observations.

In the European Territory of Russia, the precipitation in amounts less than their normal December values were only recorded in the northern territories and, partially, in the Volga region. Further southwards, the normal figures in certain areas were exceeded by 1.5-2.0 or more times. These areas were the Lower Volga, Crimea and the Black Sea coast of Caucasus. In Crimea, the total precipitations were record-breaking. Here and there, rains turned to snowfalls that resulted in a temporary snow cover. Heavy snowfalls occurred across the South of the Central Federal district in the end of the month. Fresh snow in the Kaluga, Tula and Ryazan regions could be up to half a metre in height.
The precipitation in Urals was typically as normal, but could be 1.5-2.0 times greater in quantity in the North. The record quantity was measured in the South Urals (Kurgan Region) and in its bordering areas of West Siberia. In total, the precipitation in most parts of Siberia was normal everywhere excluding the South areas where it was scarce: the Novosibirsk and Kemerovo regions, the Altai Territory and the South of the Krasnoyarsk Territory.
The abundance of precipitation in the South of the Far East, such as in the Amur Region and the South of the Khabarovsk Territory, co-existed with its scarcity in the North comprising the Eastern Yakutia, Magadan Region and Chukotka Autonomous district. The top quantities of precipitation recorded in the Kamchatka were more than 30-40 mm per day in some places.
Small precipitation amount was observed in Mongolia and in North China. But the precipitation totals were much greater than their normal amounts in other territories of China, especially in the South, East and North-West, by 2-3 or more times greater in some places.
The precipitation in the South-East Asia was also either as normal, or excessive. The latter primarily pertains to Thailand, Malaysia and Philippines where people died due to heavy rains and landslides. In spite of rare rains in the most part of Vietnam, individual showers in the middle of the month caused floods in the central part of the country.
Many rains were driven by cyclones in the Eastern Mediterranean. In the Near East and in West of Iran, daily accumulations of atmospheric moisture reached 20 to 40 mm. Snow was sweeping in the mountains.
Mediterranean cyclones brought rain moisture to the coasts of Egypt and Libya. Many other rains in North Africa hit the coast of the Gulf of Guinea. Heavy showers poured down on Kampala, the capital of Uganda. It was dry in other territories of the continent.
In the South of Europe, viz., in Portugal or Spain, in the south coast of France, in parts of Italy and in Balkans, the total monthly participation was scarce. Yet, heavy rains were observed there from time to time. Thus, showers in the Cote d'-Azur brought 60 mm of atmospheric moisture for a single day. The remaining Europe received plenty of precipitation. Up to 20 mm of rain water per day were observed in the UK and in Norway. In Belarus, Ukraine and Trans-Dniester, the total daily precipitation in certain places reached a half of the normal monthly amount. New records of precipitation were set. Much precipitation covered the Central Europe. In Germany, Austria and Switzerland, daily rain and snow totals exceeded 20 mm. However, in Europe, little snow was reported in December: even in the Scandinavian countries, a stable snow cover persevered in the North only. Yet the total monthly normal amounts of precipitation in the East and North of Europe were occasionally exceeded by 1.5-2.0 or more times.
Showers and heavy snowfalls were harrowing the USA all through December. Snowfalls along with freezing rains in the first and second decade poured down onto North and South Carolina, Georgia, Alabama, Tennessee and Virginia. The amount of fallen snow was as large as 50 cm in some places. The transport communication was damaged, power transmission lines were broken, and hundreds of thousands of people were left without electricity. In the third decade, the forces of nature attacked Kansas, Nebraska, Minnesota, Louisiana, as well as North and South Carolina again. Heavy snowfalls resulted in traffic jams, cancelled flights, and fatalities. The precipitation ratings throughout a large part of the country were exceeded by 2-3 or more times. The same fate was faced by the North of Mexico.
The situation was vastly different in Canada. In this country, the normal values were only exceeded in polar regions, while the precipitation in other territories was scarce, or even absent at all in some Western areas.
In the most part of the Northern Hemisphere, the yearly totals of participations were approximately normal. The figures were conspicuously higher in West China, the East and South of the USA and the countries in the Gulf of Guinea. The year 2018 was rainy for the Near East countries. The precipitation deficit was perceivable in India, in the Middle East, in Central Asia and in certain West-European countries.
The annual amounts of precipitation in Russia generally reached their normal values. Their shortage only exhibited in a few areas of the Volga region, in the South of the Russian Plain and, partially, in the North-East territories of the country.
The December precipitation in Moscow amounted to 53 mm. This is close to normal. The annual amount was also at its normal level of 629 mm. August and November were very dry in the capital, with less than one third of the normal amount produced in each of these months. On the other hand, the normal values were exceeded by more than 1.5 times in January and February.