What's the weather like for September 2024? Three major forecasting centers agree. The heat won't let up. Long-range forecast

Seasonal forecasters using the largest global meteorological models, from America to Russia, agree – September in Europe will be warm. Each calculation of the forecasted temperature deviation from the norm is embedded in positive values, which means warmer weather than usual. And although estimates of this thermal anomaly, or deviation from the September norm, vary, they mean more warm days than cold days. These general calculations are echoed by more detailed medium-term models, which paint wedges of warmth reaching from northern Africa and the Middle East to Poland, although interspersed with intrusions of specific cold. The temperature in September is expected to rise to 30 degrees Celsius in the first half of the month, with sunny skies, of which there is expected to be plenty, and much less rainfall.

Temperature forecasts for the first week of September are dizzying, raising the question of whether this year's September will be similar to last year's, the warmest on Earth in the 174-year history of meteorological measurements. In Poland, on September 13, 2023, the following cases were recorded: Opole as much as 31.9 degrees Celsius, and at the end of the month the temperature managed to exceed 28 degrees Celsius, while the average temperature of the month was almost 4 degrees Celsius higher than the average of the three previous decades. Will it be similar this year? A lot can still happen, but summer will be slowly leaving.

At the beginning of September, meteorological autumn begins, but the temperature does not want to drop permanently and the sun does not want to hide behind the clouds. Although the models for the first half of the month show thermal summer, with daily temperatures above 15 degrees Celsius, such weather is already beginning to alternate with thermal autumn, which is characterized by an average daily temperature between 5 and 15 degrees Celsius. However, the models lack a clear western, rainy and windy air circulation, and instead show circulation from the south and the north, which indicates a conflict between heat and cold.

Let's start with the hottest variant for September, calculated by the US National Oceanic and Atmospheric Administration (NOAA), which is breathtaking. Because the deviation from the norm in the average temperature forecast for September, depicted on the map of Europe in the form of orange and red spots from the Aegean Sea to the polar archipelago of Svalbard, offers summer prospects. In Poland, this deviation would be lower than in the previous record year and range from 3°C in the Lublin and Podkarpacie regions to 1°C on the Coast. Meanwhile, there should be less rainfall than usual, as the totals are forecast to be negative throughout the country, with the strongest rainfall in the southeast. making the Lublin region, the region with the largest number of sunny days in summer, an ideal place for early autumn pilgrimages.

The hot American forecast is echoed by the calculations of the European Centre for Medium-Range Weather Forecasts. According to ECMWF, the beginning of September is supposed to be similar to August thermally. The deviation is supposed to be smaller than in the American version, because it is supposed to be about 1°C from the multi-year norm. However, you can see the warmth lurking south of Poland, spreading from northern Africa to the Carpathians. It will be able to penetrate Poland from time to time, because it will not be blocked by multi-day rainy lows coming from the Atlantic, because the model estimates less rain rather than more, especially lowering the totals over the southeastern regions of the country. Only the coast would be brushed by fronts with heavier rain. Such a distribution of the deviation of rainfall totals means the dominance of a sunny high over southeastern Europe plus a developed wedge of high from the Azores into Europe and the continuation of the blockade for cloudy Atlantic low vortices. They would only be able to move over the northern reaches of the continent, from Scotland, through Scandinavia, to Russia. Only shallow bays with moderately active cold fronts could penetrate into Poland from time to time.

The forecast model of the Russian meteorological and hydrological service Roshydromet also paints warm colors for September on the map showing the deviation of the average temperature from the norm over western Russia and the countries between it and Poland. They are to be covered by warm air masses significantly increasing the temperature, which means that the heat will remain in Central Europe. The deviation to the plus side is to be at least 1°C and this with precipitation below normal.

Thus, according to the most important models in the world, the average September temperature for the last thirty years has been Suwalk 13 degrees Celsius, Warsaw – 14.5 degrees Celsius and Wroclaw – 15 degrees Celsius will probably be higher this year. Although maybe not as high as last year.

It is now worth moving from general to specific to understand the scale of the heat wave that awaits us in the first ten days of September. The European Forecasting Centre predicts that in the first ten days of September a heat wave will flood the entire country, and the temperature deviation from the monthly norm will be about 3-4 degrees Celsius. Between September 2 and 8, we may experience several heat waves. Although the difference between the forecast temperature and the multi-year average decreases in the coming weeks, it is still expected to be warmer than usual. Until the end of the month, the deviation is expected to be up to 1.5 degrees Celsius, especially in the east and south of the country. And this with weaker than usual, occasional rainfall.

The weather in September will be shaped by high pressure from Eastern Europe and the increasingly strong low-pressure eddies over the Atlantic. And although the cyclones are supposed to stay away from us for now, they will occasionally send bays of low pressure with cold atmospheric fronts, which will interrupt the summer idyll. The fronts, as they move inland and come into contact with dry masses of warm air, are supposed to lose momentum, bringing showers and storms with intensity generally weak and moderate. Cold, injected into Poland from time to time, will bring rainfall in the next two weeks with totals, according to the GFS model, in the west of the country and Pomerania up to 20-30 liters per square meter, only in the Carpathians and Sudetes more abundant, up to 50 l/sq. m, locally larger in storms.

Hot wedges will continue to develop from the south towards us.. It is particularly strong visible on the near horizon on Tuesday and Wednesday (September 3-4). It can create conditions for the temperature to rise to 32-34 degrees Celsius at the ground, and at a height of 1.5 kilometers from 15 degrees Celsius in the north to 20 degrees Celsius in the south of the country. Even high in Tatra Mountains and the Karkonosze Mountains, we will record around 20 degrees Celsius. There is therefore a chance for another September record, i.e. early autumn, or the so-called summer, which in the second half of the 20th century settled in Poland around August 25 in Pomerania and Warmia.

During this transitional season, the average daily temperature may be in the range of 10-15 degrees Celsius. Meanwhile, in the first half of this September we can expect that the daily temperature will remain above 15 degrees Celsius in many regions, especially in the south and southeast, extending the thermal summer. Only in the middle of the month will summer come to an end throughout Poland, because for this period the GFS model predicts the development of a strong cold bay, reaching from the Arctic to the Sudetes and the Carpathians. The temperature at an altitude of 1.5 km would drop to 0 degrees Celsius above Masuria and the Suwałki Region.

So, a break in the summer weather is visible on the horizon, although the first September cold is possible as early as around September 6. The flow of polar air mass from the Greenland region may lower the temperature in northern Poland to 15-18 degrees Celsius. Later, a high-pressure ridge stretching from the Azores to Russia is to prevent the intrusion of significant cold pressed by storm lows. CFor some time, the cold will touch Poland, especially Pomerania, Warmia and Mazury. However, until the middle of the month, the warm air masses will not leave the southern regions of the country, where the temperature may rise to 28-30 degrees Celsius. Thus, the difference in afternoons between the northern and southern ends of Poland would be at least 10 degrees. C

Cold will be a constant threat in the second half of the month, but the heat from southern regions of Europe, Africa and the Middle East will not subside any time soon and will probably make an appearance more than once. All the more so because at the turn of September and October the Indian summer anticyclone tends to strengthen over southeastern Europe, extending the good weather for up to two weeks. The European model of the ECMWF center estimates that after an exceptionally warm first ten days of September, the following weeks will be moderately warm. The temperature deviation above normal would be from 1°C in the west to 2-3°C in the center and east of the country. The temperature in the afternoons may remain below 20°C, but the developing warm wedges from time to time may still raise it to 25-28°C.

For now, the autumn rain is still far away, although we enjoy the warm evenings with nostalgia and the awareness of the end of summer. Like Moomintroll, who “always liked the last weeks of summer the most, but never knew exactly why. The sound of the wind and the sea was different than usual, you could feel the change in the air, the trees stood as if waiting for something.”