With the first days of autumn after abnormally hot August, cold weather came to the ETR. Numerous minima of daily temperatures were recorded in the west and centre of Russia. Negative temperatures were measured for the first time in a number of locations, and frosts were observed in many areas. The average air temperature in the first decade was 2-4 or more degrees lower than normal. Later on, the temperatures approached the normal values, but negative anomalies still prevailed there until the end of the month. In Central Russia and in the Urals, the average air temperature in September was about the same as in the previous year.

Air temperatures in Siberia fluctuated around the normal value in the first half of the month, but the weather in the third decade became noticeably colder, and the decade-averaged temperatures turned out to be 2-3° lower than usual. In the Far Eastern Federal District, temperatures remained normal almost for the entire month, although in Buryatia and in the south of the Khabarovsk Territory, the weather was excessively hot at the beginning of September: there, the unprecedented values reaching 25-30° or higher were recorded.

The monthly-averaged air temperatures were normal almost everywhere in Russia: against a positive background of anomalies in the Russian North, in the Volga region, in the Urals and in the south of Siberia and of the Far East, and against a negative one, in Central Russia, Yakutia, in most of Siberia, and in the north of the Khabarovsk Territory. The islands of the Kara, Laptev and East Siberian Seas in the Arctic, as well as individual areas of the North Caucasian Federal District, were the only exceptions where this September was warmer than usual, by two or more degrees. As for the air temperature monthly-averaged over the entire territory of the country, this value was normal, and matched the one in September of the last year to an accuracy of 0.1°.

A zone of large positive anomalies higher than 2-4° in the Northern Hemisphere formed a wide strip spreading from North Africa through the Near and Middle East, Central Asia, Mongolia and the northern and north-eastern provinces of China, up to the Pacific coast. These anomalies were 2-4° in Mongolia, 2° or higher in China and Japan, 2-3° or higher in Kazakhstan, Kyrgyzstan, Uzbekistan and Turkmenistan as well as in the countries of Western Asia, and 2-4° or higher in Algeria, Tunisia, Libya, Egypt and Ethiopia. New temperature maxima in excess of 40° were repeatedly recorded in the countries of Central Asia. In China, this September was the second warmest in the history of meteorological observations, yielding just to the record-breaking September of the previous year. The same can be said about North Africa.

Similar to the ETR, Eastern Europe was hit by the colds at the beginning of the month. New temperature minima, some of them with a negative sign, were set in Poland, Lithuania and Belarus. But the situation improved thereafter, and temperatures remained close to normal until the end of the month, with the exception of the south of France and the east of Spain where summer temperatures exceeding 30° persisted still. The average air temperature in Europe matched its normal value, even though the weather was somewhat colder in the centre, east and south-east of the continent, and warmer than usual in the west.

In Canada, this September was the second warmest in the history of meteorological observations, with September 2012 alone even warmer by some 0.1°. The temperature in almost the entire country was 2-3° higher than usual, or 4° higher in places. The same was true about the north and west of the USA where this month was the third warmest September in history after those of 2016 and 2019. In the rest of the United States, in Mexico and in the countries of Central America, the temperatures were generally normal.

In the Arctic, the monthly-averaged air temperature was 2° higher than its normal value.

The average temperature in the Northern Hemisphere was ranked among the top five highest since 1891.

In Moscow, the month was colder than normal: its average temperature was 10.1°, implying the anomaly of -0.9°. The weather in the capital was nearly such as cold as in September a year before when the anomaly amounted to -1.1°.

La Niño remained very powerful still. In some places, negative SST anomalies exceeded 1°, and the area occupied by them extended from the tropical latitudes of the Northern Hemisphere to the tropical latitudes of the Southern one, and further along the coast of Chile. These anomalies were especially high at the equatorial and tropical latitudes of the Southern Hemisphere. The observed La Niño may already be ranked as the second strongest in the history of meteorological observations. It started in August 2020 and persisted up to now, i.e. for 26 months: only La Niño of 1973-1976 lasted even longer (for 36 months). Experts believe that the present La Niño will survive at least to the end of 2022.

Very large positive SST anomalies took place at the temperate latitudes from the coast of Japan and Kamchatka to Canada and the USA; in some of these areas, they exceeded +3…4°. Abnormally cold water was observed in the Sea of Okhotsk as well as off the south-western coast of Alaska.

As in the previous month, large positive SST anomalies (+2…3°) in the Atlantic Ocean took place at the temperate latitudes and spread across the whole Ocean from North America to Europe. Negative anomalies were almost never observed. The water temperature in all marginal seas of the European continent was above-normal.

This September, the ETR was rich in precipitation. In the central region, new daily maxima of precipitation in excess of 30 mm per day were set. In the south of the ETR, especially in the Crimea, heavy rains were also observed. The monthly precipitation totals in most entities of the Federation reached the normal value or exceeded it by 1.5-2.5 times, and were only subnormal in the Pskov and Kaliningrad Regions the west, and in the Chechen Republic in the south.

In the Urals, these monthly totals were close to normal or slightly less than that. Heavy snowfalls occurred in the south (in the Sverdlovsk, Chelyabinsk and Kurgan Regions).

In the vast territory of Siberia, precipitation was distributed non-uniformly: its amounts were normal in the north (in Taimyr and Evenkiya), in the southern regions of the Krasnoyarsk Territory as well as in the Tomsk, Omsk and Kemerovo Regions, but lower than normal in the rest of Siberia. In Khakassia, the monthly precipitation figure was just a half of its normal value despite the record-breaking rains of 40 mm per day intensity which fell in this very area. At the end of the month, snow covered the south of Siberia (the Tomsk and Kemerovo Regions, and the Altai Territory).

Precipitation throughout the Far East was either normal, or above-normal, e.g., more than 1.5 times the normal value in the Primorye and Kamchatka Territories and in the Magadan Region. Early snow hit the northern and central regions of the Khabarovsk Territory: in some places, it brought up to 20 mm of precipitation per day in the form of snow.

The summer monsoon still reigned in Asia. Abundant precipitation was recorded in Korea and in the coastal areas of China. The normal precipitation quantities in South-East Asia were exceeded by 2.0-2.5 times in certain places, and the intensity of showers could reach 40-60 mm per day. The downpours kept flooding India, Pakistan and their neighbouring countries, amounting to the normal or above-normal monthly precipitation totals in most of this territory – twice the normal figure or more in some areas of India. Disastrous torrential rains that started as early as in July continued tormenting Pakistan, and the floods caused by them claimed the lives of more than 1.5 thousand people. More than 30 million people were affected by the destruction of infrastructure, and the total damage inflicted was estimated at $30 billion. The rains in Nepal boosted the water level in the rivers above the critical marks, thus resulting in large-scale floods.

Everywhere in the Near and Middle East, as well as in Central Asia, the weather was dry, and the precipitation amounts were much lower than normal.

The same was true for most of North Africa, with the exception of the areas along the Mediterranean coast and the areas to the south of Sahara in West Africa where the monthly precipitation totals were either normal or above-normal in places. Heavy rains fell in Cameroon, Chad and Nigeria, and caused floods in Sudan.

The entire European continent, save for Scandinavia and some parts of Spain, was inundated with rains. Several times during the month, showers hit the south-east of the continent. Heavy rains in Bulgaria raised the water levels in the rivers by 1.5-2.0 metres thereby resulting in large-scale floods and landslides. The city of Rijeka in the northern Croatia was deluged by rainwater accumulating in quantities that could reach 140 mm in two hours or 287 mm in a single day. The streets in the city of Thessaloniki in Greece turned into rivers in a few hours. The level of rainwater accumulated in Poland increased by 133 mm in three hours. In the central Italy, 420 mm of rainwater, amounting to half the normal annual figure, released in a few hours. The western areas were also targeted by heavy rains that caused numerous floods and disasters in Switzerland, in the south-west of France, in the east of Spain and in Portugal. Except for the territories mentioned above, the normal monthly precipitation figure was reached or exceeded throughout the continent. In the Balkan countries, in Germany, in the central Italy and in the south-western France, this figure was exceeded by 2-3 times.

Most of the US, especially the south-west, was short of precipitation. The amounts of atmospheric moisture in the east and west of the country, as well as in California where the drought had continued for a long time, were normal or above-normal in September. Heavy rains caused floods in Alaska; the precipitation amounts in its neighbouring northern Canada were normal or about two times greater in some locations. But to the south of these areas, the amounts were noticeably lower than usual, and regained the normal values in the south-east only. A lot of rains fell in Mexico, in the countries of Central America, and in the north of South America where the rainy season was in place. In Venezuela, the rains caused floods and landslides killing dozens of people.

This September, 81 mm of rainwater fell in Moscow, amounting to 124% of the normal value.