Fifth Heat Dome Expands Across Europe: 40°C+ Highs Target Western and Central Europe

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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.

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