The key weather and climate features of May 2015 in the Northern Hemisphere
Air temperature In May, as in any other month of spring this year, the main anomaly of heat in Russia has concentrated in the European north and the Urals. The unseasonable warm was mentioned there for the entire month. The maximum temperature was recorded on the Arctic islands, in the Komi Republic, the Nenets and Yamal-Nenets Autonomous District. Mean month air temperature exceeded the norm by 4-7°C. In the Urals Federal District was the warmest May in history and in the Northwest this May was the second warmest.
Heat records were registered in other parts of Russia, for example, in the Irkutsk region in the first and in the center of the country (the Middle Volga and Chukotka) in the third decade of the month. Everywhere except the above areas, the anomalies did not exceed an average of + 1 ... 2°C. In the Far East May was even colder than normal. In the last case, there were records of minimum daily temperature to be mentioned. Frosts up to -5 ... -7°C were observed not only in the east, but also in Central Russia, Crimea and North Caucasus. In the first twenty days of the month the weather in the European territory was colder than usual. Mean decade temperature anomalies reached -2 ... -3°C.
All this has led to the fact that in Russia May 2015 is not among the warmest, but it can not be said about the whole spring. It was the fifth warmest spring in the history of regular meteorological observations, though it inferior to the record warm spring of last year for about 1 °C. So as in the spring of the last year, this time large positive temperature anomalies (up to + 6°C) had formed in the north of the European territory, in the Urals and Siberia. Everywhere in the country, spring again was warmer than normal, but this time anomalies were less than the anomalies of the last year, especially in the European territory.
The key weather and climate features of April 2015 in the Northern Hemisphere
Air temperature
The abnormal heat was recorded during the whole month in such parts of Russia as Siberia, the Urals and the Arctic Region. Throughout the month, mean decadal air temperatures exceeded the norm by 4-10 ºC. The new daily temperature maxima were registered in the North Urals, in Novaya Zemlya, in the Irkutsk Region and in the Trans-Baikal Region. The climate spring came to the Russian North three weeks earlier than usual. Yenisei broke-up in the upper reaches of the river two weeks earlier than the average.
To the west and the east of the region, in the European part of Russia and in the Far East, as it usually happens in the spring heat and cold replaced each other in the frequent manner. Thus, to the west of the Urals, the heat of the first decade of the month with the daily temperature maxima was replaced by the abnormal cold in the second decade. During that time, there were recorded the night frosts for -3…-5ºC. They were recorded not only in the Central Russia, but also in the south, where the spring fieldwork had already begun. At the end of the month, the abnormal heat returned to the Central Russia. New daily air temperature maxima were recorded in Vologda, Kostroma, Tver, Nizhy Novgorod and other places. Such a confrontation of heat and cold has led to the fact that the mean month air temperature was about normal. Only in the Crimean Federal District, Southern Federal District and in the south of the Volga Federal District the month was colder than usual, while in the north of the country (Murmansk Region, Arkhangelsk Region, Komi Republic, and Nenets Autonomous Region) it was warmer.