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

Air Temperature

With the beginning of September, summer returned to the ETR. In the first decade, average air temperatures became above-normal everywhere, 2-3° higher than normal in the north and west, as well as in the Caucasus. New temperature maxima were recorded in Karelia and Central Russia to exceed 30° in some places, and temperatures as high as that were measured in the Luhansk Region. In the second decade, temperature anomalies in the north and west of the ETR became even higher, reaching 4-6° or more degrees in the Russian North. New daily temperature highs were set in the Arkhangelsk and Murmansk Regions as well as in the Komi Republic. Meanwhile, temperatures in Central Russia returned to normal, while in some locations in the south, the average temperature for the second decade became even less than normal. In the third decade, no high positive temperature anomalies were detected in the ETR: the decade-averaged air temperatures were close to normal almost everywhere, or even sub-normal on the Black Sea coast of the Caucasus. In the last days of the month, frosts were observed, down to -7° in the south, and new daily temperature lows were set.

In the Urals, the weather remained warm until mid-month, with anomalies higher than 2-4° in the north. In the second decade, first frosts came there to the south, and in the third, record-breaking colds to the north.

The weather in Siberia kept up abnormally warm for almost the entire first decade; then, cold air masses started to dominate in the north, and warm ones, in the south. As a result, the average air temperature in the second and third decades in the north was 1-4 or more degrees below normal, whereas in the south, it was about the same value above that. At the end of the month, new temperature highs were set in the Omsk, Tomsk and Irkutsk Regions.

Air Temperature

After a hot weather anomaly in July, a gradual cooling came to the ETR with the beginning of August. In the first decade, it happened in the Central and partially the Southern Federal Districts, whereas in the north, the Volga region and the Caucasus, a moderate heat persisted still: there, the decade-averaged temperature anomalies reached +2…4° or more degrees. New temperature maxima were recorded on the Kola Peninsula, in Novaya Zemlya and in the North Caucasus, but soon, the weather there became cold as well.

In the second decade, heat was lacking almost in the entire ETR. The decade-averaged temperature anomalies in Central Russia reached -2.0…-2.5°. The weather was warmer than usual in the extreme north of the ETR only, but the colds reached even there in the third decade. Anomalies in Karelia and in the Leningrad Region amounted to -2°; sometimes, the thermometer readings dropped below zero, and new daily temperature minima were recorded. Temperatures in Central Russia and in the Volga region were subnormal still, and approached there normal values in the south only.

In the northern Urals and Siberia, the weather was abnormally hot all over the month, with the normal temperature values exceeded by 3-5° or more in each decade, and new air temperature maxima recorded repeatedly. In Norilsk and Dickson, this August was the warmest in the history of observations, and in the Arctic islands of the Kara Sea, multiple temperature maxima were measured. There, the temperature exceeded +25°. In the south of Siberia, the weather in the first decade was noticeably colder than usual, ending up with frosts and new temperature minima in some places.