A high-amplitude upper-level ridge is locking the fifth major Heat Dome of the season over continental Europe, pushing widespread afternoon temperatures past 40 °C as mid-August begins. Driven by a powerful northward warm surge, upper-air thermal anomalies will once again climb into the 99th percentile, bringing severe excessive heat across France, the UK, Italy, Central Europe, and the Balkan Peninsula.

The primary atmospheric engine behind this 5th thermal wave is a stubborn high-pressure ridge parked over the heart of the continent. As sinking air adiabatically compresses and warms the lower troposphere, peak surface temperatures across low-lying basins and plains are forecast to reach 40 °C to 43 °C, with dry continental winds keeping humidity low and rapidly depleting soil moisture.

This renewed thermal surge offers minimal nocturnal relief, as overnight low temperatures refuse to drop below 22 °C to 26 °C across major urban corridors. The lack of nighttime cooling compounds severe physiological stress for millions of residents, skyrockets energy grid demand, and maintains extreme wildfire conditions across southwestern and central Europe.

The strongest temperature anomalies are forecast across Western and Central Europe throughout the rest of this week, projected to gradually vanish from west to east late this weekend and the following week. We can see the midrange forecast for Paris, France and Prague, Czech Republic on the following chart.

Temperatures across Iberia, France, Italy and the Balkans are peaking into the mid to upper 30s this week, and they will become higher as mid-August arrives.

Forecast model animation maps below illustrate the expansion of this 5th upper-level ridge and highlight where the highest 850 hPa temperature anomalies will focus over the coming days.

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: 5th Heat Dome Builds Across Western and Central Europe

The general weather picture over the European continent this week indicates that yet another, the fifth and powerful upper-level ridge, is re-establishing over Western Europe mid-week, gradually expanding into Central Europe by the following weekend. A major Heat Dome develops and dominates the continent.

Strong ridging remains stable for multiple days through the following weekend and results in excessive heat from the Iberian Peninsula across France to England, the Benelux, Germany to the Alpine region and Italy.

The warmest air mass is trapped underneath the core of the heat dome aloft, spread across Portugal, Spain, France, the UK, and the Benelux until Friday. The most anomalous temperatures will be over France and England on Thursday.

The deep wave over the North Atlantic allows this strong warm plume to push a significant heatwave far north across Western Europe into northwestern Europe.

By Saturday, the upper-level wave over the Atlantic emerges into Western Europe while weakening, resulting in the heat dome becoming more elongated as it shifts over Central Europe and strengthening the heatwave for Germany, the Alpine region, Italy, and the northern Balkans.

This will also bring much higher temperatures into Denmark, southern Scandinavia, and the Baltic region.

So, in response to the gradual strengthening of the heat dome, the surface heatwave will deliver the highest temperatures over Spain, France, the Benelux, and England from mid-week through Friday.

The temperatures will be around 12 to 16 °C above the long-term thermals for mid-August.

By the weekend, the excessive heat expands east, as the heat dome shifts into Central Europe and the blocking High becomes more elongated on Saturday and Sunday. This will allow temperatures to climb significantly over Germany, Denmark and southern Sweden, as well as over Poland, the Czech Republic, and the Alpine region over the weekend.

A maritime air mass from the Atlantic low will gradually spread into western Europe and bring refreshment to Ireland and the UK, France, and the Iberian Peninsula.

Daytime Highs: Regional Breakdown of 40°C+ Temperature Extremes

Western Europe: England peaks near 38-39 °C on Thursday, Ireland nears the 30s

A short but intense heatwave develops in Western Europe as the Heat Dome strengthens on Wednesday. Peak temperatures will climb into the low to mid 30s across southern and central England, up to the 30s in Wales and the upper 20s over Ireland.

On Thursday, the warmest core of the dome aloft sits over northern France, the English Channel, and the UK. This results in more intense heat over England, pushing afternoon temperatures into the 36-39 °C range. Low to mid-30s will also be possible over inner Wales, while temperatures over Scotland remain in the mid-20s. The upper-20s are forecast for Ireland as well.

France: Peak temperatures from 40 to 43 °C on Thursday and Friday

Low 40s will be back into much of France on Thursday, thanks to a heat dome aloft strengthening and expanding northward. The highest temperatures are likely to reach into 42-43 °C over western, central and southwestern France.

Just a tad lower temperatures are forecast for Friday, but will reach into the low 40s again across many regions in France.

Iberian Peninsula: 42-44 °C back into south-central Spain, Portugal nears 40 °C

Excessive heat into the low to mid-40s establishes over the Iberian Peninsula by Thursday, with both Spain and Portugal experiencing much higher temperatures than so far this week.

The peak temperatures on Thursday and Friday will reach into the 42-44 °C range across heat-prone valleys of southern Spain; the low 40s will also be over the Ebro Valley on both days. South-central Portugal should reach 37-40 °C on both days as well.

Central Europe: Germany and Benelux near 40 °C on Friday and Saturday

Friday will be the hottest day of this 5th heat dome and heatwave for the Benelux and Western Germany, with peak temperatures climbing into the 36-40 °C range across Belgium, Luxembourg, and the southern Netherlands.

On Saturday, the shift of the heat dome further east sends temperatures much higher over the rest of Germany, reaching western Poland and the Czech Republic as well. Hotter temperatures will also continue into Sunday.

Lower temperatures will gradually spread across Western Europe over the weekend.

Italy and the Balkans: Peak Temperatures 38-40 °C again over the weekend

Until Friday, the hottest air mass will remain over Western Europe, but then it will also significantly warm up over Central Europe, Italy, and the Balkans over the weekend. Temperatures will be back into the 30s across Italy and north-central Balkan countries, challenging 40 °C in the lowlands again.

The hottest air mass will be over the Po Valley and Tuscany in Italy, and eastern Croatia, Hungary, and northern Serbia (Pannonian plains) in the Balkans.

We will continue to monitor the evolution of the weather pattern and update the forecasts accordingly. Long-term trends suggest a pattern flip may finally be coming up next week. Stay tuned for updates.

PivotalWeather and WXcharts provided images used in this article.

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