MAIN WEATHER AND CLIMATE TRAITS IN THE NORTHERN HEMISPHERE AS OF MAY 2025

 Air temperature

Cold weather that came to the ETR at the end of April remained cold in the ETR for the first and second decades of May, with the decade-averaged temperature anomalies reaching -3…-5°. In the Yaroslavl, Moscow, Ryazan, Tver, Tula, Ivanovo and Bryansk Regions, the thermometer columns dropped below zero, and new daily temperature minima were recorded – notably, for several days in a row in some places. Warmth arrived in the third decade only when the decade-averaged temperature anomalies became +2…6° all the way from the Kola Peninsula to the lower reaches of Volga. In the Russian North, new temperature maxima in excess of +25-30° were recorded.

In the Urals, abnormal heat in the first decade changed to normal weather in the second, and to the cold one in the third – with the decade-averaged temperature anomalies down to -2…-3°.

The weather in Siberia was noticeably warmer than usual in the first decade when new air temperature maxima were even measured in the north of the Krasnoyarsk Territory. Abnormal heat in the second decade solely preserved in the north, while the temperatures in the south were approximately normal. In the third decade, cold in the west came along with heat anomalies in the east of the region where the thermometer readings rose to +30-35° in the Krasnoyarsk Territory.

In the Far East, frosts at the beginning of the month reached -20° in Chukotka where the weather was notably colder than usual. In the middle of the month, they spread to the Khabarovsk Territory, Amur Region and Trans-Baikal. Warmth in the Far East came in the third decade only, with the average temperatures 2-5° higher than normal. Daily maxima were set in Yakutia, Primorye, the south of the Khabarovsk Territory, the Amur Region, in Buryatia and the Magadan Region where the air temperature exceeded +30° in some places. The ice drift in Chukotka occurred unusually early.

In terms of the monthly averages, the air temperature in most of Russia was close to normal, but significantly higher than that (by 2° or more) in the north-east as well as in Taimyr, Yamal, Novaya Zemlya and other Arctic islands of this region. In the central and western regions of the ETR, this May turned out to be colder than usual.This year, May hit the top ten warmest in the meteorological chronicle of Russia. Given that, it was the third warmest in the ETR in the history of meteorological observations since 1891. The record-breaking warm spring 1995 and spring 2016 were the only ones even warmer. This spring was abnormally warm everywhere save for the extreme north-east of the country. In the Volga region, the average temperature of spring was 2-3° or more degrees above normal; the same anomalies were observed in Yakutia, Kolyma, Taimyr and the Kara Sea islands.

The average temperature of May in Moscow was +13.2° implying an anomaly of -0.4°. The first five months of the year 2025 were the warmest in the meteorological chronicle of the capital. The average temperature in spring was the third in the ranking list after the record-breaking 1975 and after 1921.

In most of East Asia, the monthly-averaged air temperature in May was slightly above-normal. But even this excess was sufficient for this month in China to become the third warmest in the history of regular meteorological observations in the country.

The average air temperature in the countries of South-East Asia was close to normal.

Although the air in the west of India sometimes heated up to above +40°, May 2025 turned out to be cold in the country. It hit the top twenty coldest for the entire history of observations. The monthly-averaged air temperature in the central part of the country was 2° below normal.

In Central Asia, the weather was very hot almost all the month, with the average air temperatures 2-4 or more degrees higher than normal. The thermometers would show above +35° in Kazakhstan or above +40° in Uzbekistan and Turkmenistan, and new maxima of temperature would be established.

In most of the Near and Middle East, the weather was noticeably warmer than usual (with the monthly-averaged temperature anomalies of +2° or greater).

In North Africa, the average temperature of May was about normal.

This May in Europe was cold, most conspicuously in the eastern and central parts of the continent. The record-breaking colds in the first half of the month were recorded in Germany, Poland, the Czech Republic, Belarus, Latvia, Ukraine, Romania, Moldova and Bulgaria. The thermometers in a number of locations in Latvia dropped below zero, which had not been observed in May before. Similarly, negative air temperatures were measured at weather stations in Belarus and Ukraine. Light frosts were noted in Germany and Poland. These colds have not been seen in Romania and Moldova since the middle of the previous century. The average May temperature in the west of the continent was close to normal. New daily maxima of air temperature were established in Great Britain.

In Canada, the cold on the Atlantic and Pacific coasts confronted the warmth in the central provinces of the country: in the former, the monthly-averaged air temperature anomalies reached -1…2°, and in the latter, +2° or above. In most of the US, and in the countries of Central America alike, the monthly-averaged temperature was normal.

This May, the monthly-averaged air temperature over the Northern Hemisphere was awarded the second rank in the meteorological history (to an accuracy of 0.1°C alongside 2020), yielding to the last year's May only.

The average temperature of spring 2025 had the same rank, but now along with 2016, the year 2024 remaining the leader. In most continents, the average temperature of spring was above normal: 2-3° above in Eurasia and 2-4° above in the extreme north of America. This spring entered the top five warmest in the history of the USA, China, Europe, North Africa and the Arctic.

Sea Surface Temperature

Even though El Niño, the warm episode of the Southern Oscillation, ended already a year ago in the equatorial Pacific and replaced by a neutral phase, the monthly-averaged SST remained record high: in May, it reached the second maximum in the history of observations, yielding to the record breaking value of May 2024 only. Moderately cold water was observed at the equatorial and tropical latitudes of the Pacific Ocean in the Northern Hemisphere, and high positive anomalies, at the sub-tropical and temperate ones. Abnormally cold water was also registered in the Bering Sea in the north.

As for the Atlantic Ocean, the average SST was above-normal over the most of its surface in the Northern Hemisphere. Large positive SST anomalies were measured in the western subtropical part and in the east of temperate latitudes, in excess of +2° off the coast of Europe. The temperature in the Barents Sea in the north was noticeably higher than normal; abnormally cold water concentrated off the coast of Canada and Greenland, and in the Norwegian and Greenland seas.

Precipitation

Precipitation in May was normal or above-normal in a significant part of the territory of the Russian Federation. Sub-normal atmospheric moisture was only received in the southern regions of the Central Federal District, in the Penza Region and the Republic of Mordovia in the Volga Federal District, in the south of the ETR (Crimea, the Zaporozhye Region and the Northern Caucasus), in Evenkiya and the Irkutsk Region in the Siberian Federal District, and in Trans-Baikal, Kolyma, Chukotka and Sakhalin in the Far Eastern Federal District. At the same time, the monthly precipitation totals in some constituent entities of the Federation were 1.5 to 2.5 or more times greater than normal. Those entities were the Pskov, Vologda, Kostroma, Ivanovo, Kirov, Ulyanovsk and Samara Regions, the Republic of Mari El, the Kurgan and Tyumen Regions, the Republic of Tyva and the Kamchatka Territory.

During the month, record-high precipitation was observed in different regions of the country, including the central region in the first days of May where it fell in the form of rain and snow, and in some places even created a new snow cover. At the same time, new daily maxima of precipitation totals were reported in the Primorye and Kamchatka Territories, while in the middle of the month, record-breaking rains fell in Yakutia and Tatarstan where new maxima of precipitation totals were recorded as well. In the third decade, record highs were set in the south of the Urals and of Western Siberia, and in the north and north-west of the ETR.

Spring precipitation, i.e., the one that fell from March to May, was abundant as a rule, but was clearly lacking in the Black Earth Region.

The weather in most of China was dry, major rains falling in the south and east of the country where the precipitation totals were normal or above that: heavy rains fell in the southern provinces of Guangdong, Guangxi, Jiangxi, Zhenjiang and Fujian.

The countries of South-East Asia received normal or above-normal precipitation except for the northern regions of Vietnam where it was deficient.

Rains flooded India; there, by the end of May, the precipitation totals notably exceeded the normal amounts. In a number of states, floods and landslides killed dozens of people.

Almost no rains fell in the countries of Central Asia and of the Near and Middle East; they were only observed in some regions of Kazakhstan and Turkey as well as on the coast of the Red Sea.

Powerful and prolonged showers in North Africa led to flooding in Nigeria and caused harm in Somalia. Save for these countries, normal precipitation was reached along the coasts of the Mediterranean Sea and the Atlantic Ocean. In the rest of the territory, the weather was dry.

Drought came to Central and Western Europe, whereas in the east and north of the continent, it was rainy, and the monthly precipitation totals were normal or exceeded. Record-high precipitation was measured in Belarus and Ukraine, and heavy downpours caused flooding in Bulgaria. As reported, the drought in the UK was the most severe since the middle of the last century, and in Germany, precipitation during this spring amounted to a mere third of the normal value.

Precipitation in May was sub-normal in most of Canada; it was normal in the east of the country only. Heavy rains that caused floods fell in the east and south of the USA, while the weather in the west of the country, and in the north of Mexico alike, was dry.

In Moscow, the monthly precipitation total was 73 mm: this is 120% of the normal amount.

Hydrometcentre of Russia