A high-amplitude upper-level ridge is expanding eastward across Central Europe and the Balkan Peninsula, locking in a widespread heatwave with daytime highs above 40 °C through the first week of August. Driven by a persistent Heat Dome synced with an Omega block pattern, an exceptionally warm and dry air mass continues surging from North Africa, pushing upper-air thermal anomalies into the 99th percentile with excessive heat across northern Italy, Hungary, Croatia, Serbia, and the surrounding regions.
The main atmospheric engine driving this multi-week heat event is a stubborn high-pressure system parked directly over the heart of the continent. As sinking air compresses and warms the lower troposphere, peak surface temperatures across low-lying river basins, including the Po Valley and the Pannonian Basin, are forecast to range from 40 °C to 43 °C, while continental dry winds keep humidity low and accelerate soil moisture loss.
This prolonged thermal surge offers minimal nocturnal relief, as overnight low temperatures refuse to drop below 22 °C to 26 °C in major urban centers.
This lacking nighttime recovery compounds severe physiological stress for millions of residents, accelerates agricultural drought, and significantly heightens explosive wildfire conditions across southern Europe and the western Balkans.
Forecast animation maps below illustrate the expansion of the upper-level ridge into Eastern Europe and the Balkans, highlighting where the highest 850 hPa temperature anomalies will cluster through the upcoming weekend.
Before we dig into details, let’s examine what the Heat Dome is and why it is important to understand its dynamics.
Atmospheric Dynamics: How High-Pressure Heat Domes Compress and Trap Air
When significant, record-breaking heatwaves occurred in the United States, Canada, and Europe in the past, the Heat Dome was a contributing factor. The heat dome is usually the dominant feature of summer weather patterns on both continents.
We refer to this phenomenon as a heat dome when extremely high temperatures develop. Here’s how it works and why understanding it on a broader scale is essential. The upper-level ridge pattern, or very warm air mass in the higher altitudes, also known as the Upper High (or blocking High), usually forms the heat dome. This weather pattern brings high, and sometimes record-breaking, temperatures to the region below.
This term is used when a broad area of high-pressure air parks over a large portion of the continent. If the event is remarkably stable and extreme, it usually lasts several days or weeks.
The heat dome works like a lid on a pot. The extensive dome traps warm air at all levels underneath, with layers sinking toward the ground. Therefore, the air mass becomes anomalously warm at the lowest elevations and extremely hot near the surface.
Health and Grid Impacts: Managing Nocturnal Heat Stress and Heat Index Extremes
Excessive heat in heat domes can significantly impact human health and be dangerous to particularly vulnerable populations, such as elderly individuals, children, and those with pre-existing health conditions that can be worsened by extreme heat.
Due to prolonged exposure to high temperatures, construction workers, farmers, and other long-hour outdoor workers are at increased risk of heat-related illnesses. People living in poverty are also more susceptible to the fatalities of heat domes, as their houses are often built with heat-trapping surfaces such as concrete and asbestos.
Heat exhaustion occurs with prolonged exposure to high temperatures. It leads to dehydration, dizziness, and, in more severe cases, heat exhaustion can progress to heat stroke.
High relative humidity during a heatwave can also significantly affect the body. For this reason, we use the Heat Index to represent the perceived feel of scorching-hot temperatures and high humidity. It illustrates the natural relationship between temperature and humidity.
When the air mass has a temperature around +35 °C, humidity below 60 percent is much less challenging than when the humidity is very high, e.g., above 80 %. Thus, the actual feel temperature would be near 50 degrees Celsius. Heat waves have also been associated with increased rates of heart attacks, strokes, and respiratory illnesses.
Our additional article, Health risks during a heatwave and sweltering hot weather, provides further details on the health risks.
Beneath these staggering meteorological statistics lies an even more grim threat. The danger is magnified by suffocating so-called ‘tropical nights’ where temperatures don’t drop below 24 °C, denying the human body its vital window to cool down.
Synoptic Setup: Heat Dome Expands Across Central and Eastern Europe
The general weather picture over the European continent this week indicates a persistent strong upper-level ridge sitting over Central Europe, gradually expanding into Eastern Europe. An upper wave emerges into western Europe by mid-week, increasing southwesterly flow between the two large-scale features.
Strong ridging remains stable for multiple days through the following weekend and results in excessive heat from the Alpine region, the Italian plains, the Panonian plains and Ukraine to the east.
The warmest air mass is trapped underneath the core of the heat dome aloft, spread across Germany, the Czech Republic, Poland, Slovakia, Austria, northern Italy and Slovenia by midweek. The most anomalous temperatures will be over Poland on Wednesday.
The upper wave in western Europe does bring additional maritime air mass from the Atlantic, thus supporting further refreshment for the UK, France and most of the Iberian Peninsula.
By Friday, the upper-level wave over Western Europe strengthens, resulting in the heat dome over central Europe becoming more elongated and shifting further east-southeast over Eastern Europe and the Balkan Peninsula.
This will bring much higher temperatures also into Balkan countries, which were spared from the most extreme temperatures through the beginning of this prolonged heatwave since mid-July.
So, in response to the gradual eastward expansion of the heat dome, the surface heatwave will deliver the highest temperatures over Germany, the Czech Republic, Slovakia, Austria, Hungary and Slovenia on Tuesday.
By Wednesday, the core of the most anomalous temperatures shifts more towards the east with the dome aloft, so the higher temperatures also expand across Croatia, reaching Serbia and Romania. It cools down from the Benelux into Germany under the effect of a western wave.
It remains extremely hot on Thursday, especially from eastern Slovenia and Croatia into Hungary, Slovakia, northern Serbia, Romania and Ukraine. This is forecast to be the hottest day for the northern Balkans and Eastern Europe this week.
The excessive heat for the region continues into Friday, which will also expand into western Russia and further south across the Balkans, reaching Bulgaria and Greece as well.
Daytime Highs from 40 °C to 43 °C from Central to Eastern Europe and the Balkans
Italy and the Balkans: Peak Temperatures up to 43 °C through Thursday
With more westerly winds and the pattern shifting into a more elongated ridge, temperatures are increasing for the northern Italian plains and the Pannonian plains this week. Starting Wednesday, temperatures will reach the low 40s over the Po Valley, and up to 42 °C from Hungary to eastern Croatia and northern Serbia to western Romania.
By Thursday, temperatures are forecast to peak even higher, reaching up to around 43 °C in the heart of the Panonian plains.
Central Europe and surroundings: Tuesday to Wednesday push into the upper 30s
Another hot day for Germany, Eastern Austria and the Czech Republic will deliver excessive heat on Tuesday, peaking from 36-38 °C in Germany, 37-40 °C in the Czech Republic and up to 40 °C in the Eastern Austria plains. It will be even hotter across Hungary and part of Slovakia.
While the ridge aloft expands and moves east, the influence of the maritime air mass into western Europe remains persistent, so it gradually cools the air mass on Wednesday, pushing the hottest air mass as far east as Eastern Germany, Western Poland, and Western Czech Republic and Austria.
Eastern Europe: Late week delivers 40 °C into Ukraine, Eastern Poland and southern Belarus
The core of the ridge will become strongly elongated after Wednesday, thus pushing the hottest airmass across Eastern Europe. It will persist also into Friday before the shallow front emerges from the west.
The highest temperatures from Wednesday through Thursday and Friday in this part of Europe will be from 38 to 41 °C in the valleys, with also ‘tropical nights’ and temperatures not falling below low to mid-20s in some parts.
Mid-range trends suggest a potential new Heat Dome could expand into Western Europe next week
The general trends on the weather pattern after this week are in good agreement that yet another strong ridge could expand into southwestern, western, and central Europe next week. Its more precise position is still uncertain as we are looking nearly 10 days ahead, but ensemble models are trending this way.
With the large ridge developing, it would also establish a new persistent Heat Dome that would continue to support excessive heat through mid-August.
The following chart hints at the areas that would gradually warm up again next week, experiencing a new significant heatwave across Portugal, Spain, France, and towards the Alps. The new heatwave would also gradually expand into the British Isles.
The ongoing ridge over Eastern Europe and the Balkans would collapse the following weekend.
We will continue to monitor the evolution of the weather pattern and update the forecasts accordingly. Stay tuned for updates.
PivotalWeather and WXcharts provided images used in this article.
See also:
Super El Niño Drives an August Weather Shift as Fall and Winter Signals Strengthen