Annual average air temperature in Russia is formed under the influence of climate-forming factors of different scales. Macroscale factors include atmospheric circulation, radiation regime, and the nature of the underlying surface, determined by the latitude of the terrain, the degree of continentality, and the macrorelief. In addition to macroscale factors, thermal conditions are influenced by local conditions: meso and microrelief, the nature of vegetation and soil, the proximity of water bodies, etc. The size of the country, the heterogeneity of the underlying surface and the variety of circulation processes that occur under these conditions leads to a complex picture of the spatial and temporal distribution of air temperature. The distribution of air temperature in Russia is mainly due to the winter nature of temperature distribution, since the period of time characteristic of the natural winter period is longer in most parts of the country. The boundaries of the natural climatic seasons are the dates of the onset (cessation) of frost. It is obvious that the duration of these seasons in different physiographic conditions is not the same. The duration of the seasons is determined by the latitude and altitude of the place above sea level, the degree of climate continentality, landforms, etc. Of particular importance are the features of atmospheric circulation, the influence of which often overlaps the value of the latitude of the place. In the European part annual average air temperature in Russia are mostly positive. Only in the foothills of the Northern Urals, inland areas of the Kola Peninsula, and in the basin of the Pechora River, they are 1–3 ° C below zero. The highest annual air temperatures are observed on the Black Sea coast of the Caucasus and the southern coasts of Dagestan (10–11 ° C).
In the Asian part of Russia, the coldest are the central and eastern regions of the Republic of Sakha (Yakutia). In the valleys of the Yana and Indigirka rivers, the average annual temperature is –15 … –16 ° C. Low annual air temperature in Russia in the Arctic basin. Here, the highest average annual temperatures (–1 … –5 ° С) are noted in the extreme west of the Arctic Ocean, and the lowest (–13 … –14 ° C) on the coasts and islands of Laptev and East Siberian seas. In the Chukchi Sea, annual temperatures are slightly higher (–10 … –11 ° C), and in the Bering Strait they reach –6 … –7 ° C. Average annual temperatures –6 … –7 ° C are also characteristic of the central part of the East Siberian plateau and north of Transbaikalia. Positive annual temperatures in the Asian part of Russia are noted in the south of Western Siberia, in the Khabarovsk and Primorye territories, in the south of Sakhalin and Kamchatka. Their highest values are observed in the south of Primorsky Krai and are +7 +9 ° С. The amplitude of the annual course of air temperature in Russia depends both on the degree of continentality of the climate and on the nature of the relief. It does not depend much on geographic latitude. The magnitude of the amplitude is most dependent on the degree of climate continentality.
The smallest annual amplitudes air temperature in Russia are 8–10 ° С and are observed on the western coast of the Barents Sea, where they are caused by relatively warm winters and cool summers.
On the shores of the Black Sea, at high winter temperatures, summer is very high, so the value of the amplitudes here increases to 18 ° C. The same order of magnitude has the values of annual amplitudes in the Far East, in the region of the Commander Islands and in the south of the Kamchatka Peninsula. In Primorye, where the influence of the winter moraine prevails over the summer, the annual amplitudes increase to 25–30 ° C. As we move deeper into the territory of Russia, the magnitude of the amplitudes of the annual variation of temperatures increases. In the European part of Russia, their values vary from 25–26 ° C on the western borders of Russia to 30 ° C in the Pre-Urals, and on the Asian part from 30–40 ° C in Western Siberia to 40–50 ° C in Eastern Siberia. In the Tuva Basin of Sayan, annual amplitudes reach 50–52 ° C. Maximum amplitudes (up to 63 ° C) are observed in Eastern Siberia in the Verkhoyansk Range and cause a sharp contrast between the warm summer and the very cold winter.
The daily variation of air temperature in Russia is caused by the course of the radiation balance, which, in turn, depends on the height of the sun, the length of the day, the mode of cloudiness, etc. In the long-term daily course, the minimum average hourly temperatures in most of the territory of Russia are noted before sunrise and shift from 7–8 hours in winter to 3–5 in summer. In the Arctic regions, during the polar night, air temperature changes during the day on average do not exceed 0.1–0.3 °
C during the day. Here, the daily variation of air temperature in the dark season is opposite to the usual, i.e. the maximum temperature is noted at midnight, and the minimum – at around midday hours, which is associated with a kind of daily wind speeds in the polar latitudes from October to February, with a maximum at night and a minimum during the day. The time of occurrence of the average hourly maximum depends on the location of the stations. In continental areas, the maximum temperature is noted in winter at 13-14 hours, and in summer – at 15-16 hours. On the coasts, as a rule, the highest temperatures are observed at 13-14 hours throughout the year, but on the southern coasts of Primorye, Sakhalin and Kamchatka the winter daily maximum is observed around 14-15 hours, and in summer it shifts to earlier periods – 13-14 hours January is the coldest month in most parts of Russia. The lowest January air temperature in Russia in the European part of Russia (up to –20 ° С) is observed in the northeast, in the valleys of the Usa and Shchugur rivers, where in some years it can drop to –30 ° С, which is associated with stagnation of cold air masses in front of the Ural the ridge. Relatively high air temperature in Russia in January are on the Black Sea coast of the Krasnodar Territory (Novorossiysk +1, 5 ° С, Sochi + 4 ° С), which is caused by the proximity of the sea and the closeness of the coast from the cold northeast winds by mountain ranges.
Clear anticyclonic weather prevails in Western Siberia in January. January temperature varies from –15 … –20 ° С in the south to –28 … –30 ° С in the north. Here the warmest area is Lake Teletskoye in Altai, where the average monthly temperature in January is not lower than –10 ° C. The winters of Eastern Siberia are exceptionally harsh. The region of the lowest average January temperatures in the world (–42 … –45 ° С) covers the interfluve of the Lena and Kolyma rivers, and in the region of the Oymyakon depression and the Yansk intermountain depression there is a “cold pole” with January temperatures down to –48 … –50 ° С. The highest winter temperatures in the Asian part of Russia are observed on the islands of the Kuril Ridge. Here, the influence of the winter monsoon weakens noticeably and the temperature of the coldest month, February, is –6 –7 ° С.
A characteristic feature of the distribution of winter air temperature in Russia is an inversion increase in their values with altitude in mountainous areas. In terms of the number and depth of strong inversions, regions of central and northeastern Yakutia hold the first place in the world. Radiation cooling and anticyclonic downward movement of air in these areas create favorable conditions for inversions with a jump of more than 10 ° C and sometimes up to 20 ° C.
The calendar dates of arrival of spring do not coincide with the boundaries of the spring season, defined as the date of the steady transition of air temperature through 0 ° С. In the European part of Russia, the transition through 0 ° C takes place on average in the south in the second decade of March, in the central regions and in the Middle Urals in the second decade of April, and in the Arkhangelsk region and the Komi Republic it is delayed by another decade. In general, we can talk about the transition to the frost-free period in the European part of Russia by the end of April. Here, only in the regions of the Atlantic Arctic until the end of May does the air temperature in Russia remain below 0 ° C. In the Siberian Arctic belt, the transition of temperature through 0 ° C is still about 1-2 weeks behind. In more southern areas, the transition time in the western and eastern parts of Russia approximately coincides. In April, the average air temperature in Russia begin warm. Very low temperatures persist in the Arctic. On the European territory of Russia, the zero isotherm runs along the border of the Murmansk and Arkhangelsk regions, the Republic of Komi and, skirting the Ural Mountains, descends along the southern border of the West Siberian Plain to the foothills of the Altai. In the Asian part of Russia in Western Siberia, there is a deflection of isotherms to the south, associated with the slower warming up of the highly exhausted central regions of Eastern Siberia. In the eastern regions, only in the south of the Khabarovsk Territory, in the Amur Region and on the islands of the Kuril Ridge, warm temperatures are observed.
The time of summer maximum air temperature depends on the degree of continentality of the area. In the mainland, the maximum average monthly air temperature is predominantly observed in July, and on the coasts – in August, which is associated with the weakening of the cooling effect of the sea by the end of summer.
In July, the latitudinal distribution of air temperature is finally established. July has the lowest temperatures in the Arctic. Although, with the exception of the central part of the polar basin, July temperatures in the Arctic are positive, their values do not exceed 4–5 ° С, and in the Kara Sea region only slightly above 0 ° С. As it moves southwards, the temperature quickly rises due to the transformation of Arctic air masses over the continent. The highest temperatures in July are observed in the Caspian region and in the Republic of Dagestan. Here, the continental air of temperate latitudes, passing over the arid steppes of the southeast and the hot sands of the Pre-Caspian Sea, is very hot and transformed into tropical. High summer temperatures (up to 17 ° –19 ° C) are noted in the central regions of Yakutia. Such values of July temperatures in the European part are traced to the south, in the areas of the Central Black Soil Region. When moving from central Yakutia eastward to the Pacific coast, there is a violation of the latitudinal course of the isotherms. Here, due to the cooling influence of the Okhotsk and Bering Seas, as well as due to the summer monsoon, July temperatures reach only 12–14 ° C, and on the Kuril Islands are 8–10 ° C.
In the fall, the fall in temperature is subject to the same laws as the rise in spring temperatures: it is most intense in the central regions of the country, slowed down on the coasts. In the annual course of average monthly temperatures, spring in the oceanic climate is colder than autumn, unlike in continental regions, where autumn, on the contrary, is colder than spring.
In October, the restructuring of the temperature field according to the winter type begins: in the European part of Russia and in Western Siberia, the temperature decreases from west to east more intensively than from north to south. Only in eastern Siberia is the latitudinal distribution of air temperature maintained. The temperature decrease from September to October ranges from 5–6 ° С in the European part of Russia to 12–14 ° С in Eastern Siberia. The most intense fall in temperature is characteristic of central Yakutia and the interior of the Magadan Region (15–16 ° C).
Most of the European part of Russia still has positive temperatures. Only in the northeast of the European territory of Russia and in the interior of the Kola Peninsula, the average monthly temperatures of October fall to –1 … –4 ° С. In the south, relatively high temperatures are maintained from 8–9 ° С at the latitude of the Rostov Region to 14–16 ° С on the coasts of the Black and Caspian Seas. In the Asian part of Russia, positive air temperatures in October remain in the south of Western Siberia, the southwestern coast of Kamchatka, on Sakhalin and in the Primorsky Territory. In October, low temperatures of –8 … –12 ° С are characteristic of Eastern Siberia, and in the northeast of Yakutia they reach –15 ° С and lower.