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

Air Temperature

In the ETR, the average air temperature in the first decade of October was basically normal except for the Russian North where the weather was noticeably warmer than usual. New daily temperature maxima were even recorded in Karelia and in the Astrakhan Region. At the end of the decade, flows of hot air from the Middle East reached North Caucasus where new maxima of warmth were set in some places as well. Conversely, new record-breaking air temperature minima were reported in the Black Earth Region, in some locations of the Volga region and in the north-west of the ETR at the beginning of the month.

In the second decade, cold weather arrived: not bitterly cold, but still bringing frosts to Crimea in particular. Overall, conditions in the ETR during the decade remained close to normal, albeit that with weakly-negative anomalies occupying a large territory.

Abnormal warmth came forth in the ETR in the third decade, when the average temperature became above-normal almost everywhere: in the Central and Volga regions as well as in the north-west, the decade-averaged anomalies of air temperature exceeded +2-3°.

In the Urals and to the east of them, the first decade was cold, with the average temperature 2-4° less than normal over a large area. The weather in the second decade became yet colder, with anomalies reaching -5…-6° in some places. Record-breaking minima of air temperature were recorded in the south of Western Siberia, e.g., in the Omsk and Novosibirsk Regions, in the Republic of Altai, in Cis-Baikal and Trans-Baikal, on Sakhalin and in the Khabarovsk Territory. First 30-35° frosts came to Yakutia and Chukotka.

In Chukotka, abnormal colds with new unprecedented lows persisted until the end of the month. The weather in the third decade was notably colder than normal in the south of the Far East as well, with anomalies down to -2° in Primorye. At the same time, warmth came to Siberia, raising the decade-averaged air temperatures to 2-4 or more degrees above normal.

All month long, the weather in the Arctic region of Russia was record warm, with extremely high temperatures on Taimyr, Franz Joseph Land and the Kara Sea islands. There, the monthly-averaged temperatures were 2-6° above normal. Also, the weather was markedly warmer than usual in the ETR as well as in the north of the Urals and Siberia. The southern regions of the Urals and of Siberia along with the entire Far East received notably less warmth than normal. The monthly-averaged temperature anomalies over a large area were down to -2…-4°.

Warmth in the west and north of the country and cold in its east balanced each other to result in close-to-normal October temperature averages in Russia, which were slightly sub-normal in the ETR, and slightly above-normal in the ATR. The monthly-averaged temperature in the Russian North was at the end of the top-five highest in the ranking list complied since 1891.

Regarding the Northern Hemisphere, this October was the third warmest in the history of meteorological observations, with its average temperature yielding only to the record-breaking October 2023 and the following October 2024, meaning that the Hemisphere remained all-time warm for three years in a row.

The weather in Mongolia and in the north and north-east of China was colder than usual, and basically normal in the rest of China, although temperatures in some regions were two or more degrees higher than usual. On the Korean Peninsula and in Japan, the figures were above-normal; still, the monthly-averaged air temperature in Hokkaido in the north of the latter country was significantly colder than usual.

Temperatures in South-East and South Asia were normal, yet against the background of weakly-positive anomalies in the first case, and against the background of weakly-negative ones in a large part of India.

In most of the Near and Middle East, temperatures were close to normal. However, the weather in northern Iran was distinctly warmer than usual (with the monthly-averaged temperature anomalies up to +2° or more), while in the southern part of the Arabian Peninsula, it was somewhat colder. On some days, the thermometer readings in Iran and Iraq rose to +35-40°, whereas in Georgia, to +30° or higher.

The thermal conditions in the countries of Central Asia varied: in the west of Kazakhstan, positive anomalies prevailed and even led to new temperature highs, but in its east, anomalies were negative and led to new temperature lows on occasional days. In the west, the monthly-averaged air temperature was 2° above normal, while in the east, it was by approximately by the same amount lower. In Kyrgyzstan, this temperature was below normal by 1-2°, in contrast to Uzbekistan, Tajikistan and Turkmenistan, where it was above normal by about the same value.

In North Africa, the average temperature in October was close to normal, with weakly-positive anomalies amounting to 1-2° in some places.

On the average, air temperatures in Europe were about normal, against the background of weakly-negative anomalies in the east and of weakly-positive ones in the west. In some regions of Spain, the normal values were exceeded by 2° or more; in the north of Norway, Sweden and Finland, situation was the same.

In Canada, the record-breaking warmth was observed, and the average air temperature reproduced the maximum dated October 1921. In the USA, October 2025 was the sixth warmest in the history of observations. The monthly-averaged air temperature was above-normal virtually across the entire continent, by 4-6 or more degrees above in northern Canada, or by two or more degrees above in the rest Canadian territory, in the US, and in the north of Mexico. Only in some locations along the Pacific and Atlantic coasts it was slightly less than normal.

In the Arctic, this October was the warmest in the history of meteorological observations, surpassing the October 2016 record by 0.1°. The monthly-averaged air temperature in Canada, in Greenland, in the north of Scandinavia, and in Russia from the Kola Peninsula to Yakutia was 2-6 or more degrees higher than normal. 

In Moscow, the average air temperature in October was +7.5°; this is 1.7° above normal.

Sea Surface Temperature

This October, the area of negative SST anomalies in the equatorial Pacific expanded remarkably. In some places over there, anomalies reached -1°, affecting the average anomaly in a part of the Ocean located in the Northern Hemisphere and shifting it below the values in the previous months, but the average SST was extremely high still. SST anomalies in other latitude zones of the Northern Hemisphere were positive almost everywhere, exceeding +1…3° at the subtropical, temperate and northern latitudes.

The average SST of the Atlantic Ocean in the Northern Hemisphere was also very high, yet did not reach the record-breaking value. High positive SST anomalies (more than 1-2°) were observed in the Caribbean Sea and in the Gulf of Mexico, off the coast of Newfoundland and in the east of the central part of the Ocean in the Northern Hemisphere. But the largest anomalies were measured at the northern latitudes of the Ocean in the Norwegian, Greenland and Barents Seas and further along the Arctic coast as far as Yakutia: there, the surface of the Ocean was 1-3 or more degrees warmer than normal in monthly terms. Positive anomalies were high in certain regions of the Mediterranean and Black Seas.

Precipitation

In October, precipitation was a frequent guest in Central Russia, in the Volga region and in the south of the ETR, with its monthly totals of about 3 times the normal value in the Donetsk and Luhansk Republics, 2.5 times in the Astrakhan Region, 2 times in the Krasnodar Territory, and 1.5 or more times in the Orel, Bryansk, Voronezh, Kursk, Belgorod and Saratov Regions as well as in the Stavropol Territory and Karachay-Cherkessia. In the rest part of the ETR except for its north-western region, they reached the normal value almost everywhere. At times, very heavy rains were falling, especially in the south of the Krasnodar Territory and in Crimea. The daily precipitation totals reached 15-30 mm, and new daily precipitation maxima were recorded.

The weather in the rest of Russia was mostly dry, but not without exceptions. Thus, Trans-Baikal received a lot of precipitation in the form of rain and sleet amounting to 20 mm per day or to 150-250% of the normal value per month, and setting new daily maxima. In the Novosibirsk Region, up to 130% of the normal monthly amount fell in the first decade already, and the snow cover height reached 20 mm. Prolonged snowstorms in the north of Yakutia and Kolyma created snow banks of record height for October; there, the monthly precipitation figure was 1.5-2.0 times the normal value. Heavy rains fell on Sakhalin and on the Kuril Islands in the form of rain and sleet, amounting to 40-50 mm per day in places.

Many rains fell in China: in the central part of the country from Tibet to the Pacific Ocean, their monthly totals were 1.5-3.0 or more times the normal value. In the north-east of the country and on the Korean Peninsula, these totals were over two normal values. Precipitation in Japan was normal.

Abundant rains were observed in the countries of South-East Asia: in places, they were of exceptional character, i.e. their monthly totals exceeded three normal amounts. In Thailand, rain fell for several days and caused massive floods that deluged vast agricultural lands.

Monsoons continued to inundate India, Pakistan and Nepal, leading to floods and landslides. The monthly precipitation totals reached two to three normal figures or more.

Precipitation shortage was experienced in the Near and Middle East as well as in Central Asia. Non-zero averages were only measured in Turkey and Trans-Caucasus in the east, and in western regions of Kazakhstan in Central Asia.

In North Africa, rains occurred in the coastal regions of the Gulf of Guinea, as well as in Sudan where a lot of rain from June to October led to floods due to rising level of the Nile and its tributaries.

Rains in Europe were especially plentiful in the south-east and east of the continent (1.5-3.0 times the normal monthly amount) and in the northern areas (up to 1.5-2.0 or more times the normal amount in some locations). Heavy rains bringing up to 100-150 mm of precipitation over several days caused floods in Bulgaria and Romania. A number of weather stations in the Baltic countries (in Latvia and Lithuania) reported new daily precipitation maxima of up to 20-30 mm or more in some places. Heavy rains also fell in western France and north-eastern Spain: in certain areas, up to 30-50 mm of atmospheric moisture accumulated, and at one location in Catalonia, more than 250 mm of rainwater fell in two days.

A lot of rain in North America went to the western US states and southern Canadian provinces neighbouring them: there, the monthly precipitation totals exceeded 1.5-3.0 of the normal figure. On the last day of the month, heavy downpour occurred in New-York bringing 75 mm of daily precipitation. Ample precipitation was also observed in Alaska and several regions of Mexico (1.5-2.0 times the normal amount for October).

In Moscow, the precipitation total in October amounted to 96 mm, which is 137% of the normal figure.