The ink is barely dry on May’s historic climate charts, and Europe is already trapped in a far more intense and potentially deadly atmospheric assault. The end-of-June weather pattern known as an “Omega Block” has paralyzed the upper atmosphere, locking in a monstrous Heat Dome and developing an Excessive Heat Wave directly over the continent.
The latest forecast models have sent shockwaves through the scientific community, projecting a thermal spike so intense that it will literally surpass hundreds of previous late-June thresholds. Some regions may even challenge their all-time heat records, normally peaking in late July.
The mechanics of this significant climate anomaly lie in the immovable omega block, acting as a lid that traps a stagnant mass of dry Saharan air and relentlessly compresses it downward. The unprecedented Heat Dome is leading to excessive heat that will be not only intense but also long-lasting, among Europe’s most intense and historic heatwaves on record.
The intensity of the Heat Dome is so powerful, with the ongoing pattern, that the compression of air masses causes temperatures to rise exponentially day after day, with no atmospheric ventilation underneath. Following May’s record dry spell, the topsoil has also been stripped of all moisture, eliminating the Earth’s natural ability to cool itself and turning major urban centers into concrete ovens. Major European cities will experience excessive heat, with Paris, London, Hanover, Frankfurt, and Brussels at its core.
Many of France’s mainland departments are under an extreme “Red Alert,” with southwestern regions bracing for a prolonged 45 °C (113 °F) plateau lasting several consecutive days. Across the English Channel, the UK Met Office has also issued a rare “Extreme Heat Warning” for an unprecedented 40 °C (104 °F) that threatens to obliterate a half-century-old June record.
From the Swiss Alps to the lowlands of Belgium, national weather services are uniformly warning of the hottest June temperatures ever recorded.
Temperatures of 42 to 45 °C are now expected from Brittany to the Pays de la Loire region in France on Wednesday, with gusts reaching 50 km/h and relative humidity below 10%. Under these conditions, an effect known as the Heat Wave Flash Drought (HWFD) event (more commonly known as the “hairdryer effect” or flash drought) is increasingly likely to develop.
The combination of extreme heat, exceptionally dry air, and sustained winds causes a sudden acceleration of evapotranspiration and the drying out of vegetation. The consequences can be a rapid, massive leaf loss, mortality of particularly sensitive young plants, severe stress for wildlife and livestock, and a risk of wildfire reaching extreme to very extreme levels.
Seeing such conditions develop as far as Brittany is simply astounding and truly historic, especially since it occurs this early in the summer, soon after the Summer Solstice on Sunday.
The temperature forecast numbers are flashing red across multiple countries, with Portugal, Spain, and France reaching low to mid-40s (110-113 °F), with many major cities facing an extended, multi-day stretch of excessive heat. Note that these temperatures are roughly 12-18 °C above seasonal averages.
Before we dig into the details about the pattern evolution in Europe, lets examine what is the main driver behind these extensive warm waves and heatwaves in general.
What is a Heat Dome?
When significant, record-breaking heatwaves occurred in Europe, the United States, and Canada 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.
How does a heat dome impact the life underneath?
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.
Beneath these staggering meteorological statistics lies an even more grim danger. Extreme heat is a silent killer, and this current dome has already turned lethal, claiming lives across France and Spain within its first days. The danger is magnified by suffocating so-called “tropical nights” where temperatures don’t drop by 24 °C, denying the human body its vital window to cool down.
Because centralized residential air conditioning is rare across Europe, emergency rooms are bracing for an onslaught of life-threatening heat stroke. 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.
A historic Heat Dome develops and further intensifies across Western Europe
A powerful blocking High dominates the weather pattern over the North Atlantic and Europe through the remainder of June, resulting in a significant warm plume expanding beneath the unprecedented Heat Dome.
Throughout this week, the extensive upper-level ridge will gradually expand further north and east, dominating most of the European continent at least until early July.
The medium-range global model ensemble guidance (from ECMWF and GFS) indicates that 500 mbar geopotential heights will reach record levels by the end of June, climbing exceptionally high as the upper-level subtropical air mass expands northward.
These anomalous upper-level heights at 500 mbar represent a highly anomalous late-spring tropospheric setup. With sinking air (compression and warming at the surface), surface temperatures have exceeded the 40 °C threshold since Sunday and will continue to rise through the next weekend, affecting Iberia, France, England, parts of Benelux and western Germany, Italy, and, over the weekend, the central Balkan peninsula.
The sinking air within the heat dome also translates into rising pressure beneath it, the mid-40s across France and Iberia, and by the weekend into early next week, developing into a surface high-pressure system centered over the west-central part of Europe, with much higher-than-usual pressure values.
No significant disturbances are foreseen, so the high pressure and the excessive heatwave will be long-lasting. As the upper ridge expands over time, the surface high-pressure area will expand as well. It will bring well-above-normal surface pressure for most of the continent, except for far southeast Europe, where conditions will remain below normal seasonal averages into the end of June.
The significantly warmer air mass is rapidly expanding northward, with temperatures continuing to climb day by day across western Europe.
Until Thursday, the warmest and most anomalous air masses will be over Spain, Portugal, France, Benelux, and the UK. Temperatures are forecast to gradually spread further north and east over the following weekend.
Near-surface temperature anomalies were already extreme across Spain, Portugal, and France on Sunday, and are surging northward across the rest of western Europe in the coming days. By Tuesday and Wednesday, the temperatures will be around 15-20 °C above normal for late June, potentially even higher locally with the most anomalous air mass across western and central France, Benelux, and the southern UK.
Towards the weekend, as the core of the Heat Dome shifts and expands eastwards, the most significant temperature anomalies will spread across Germany, Denmark, southern Scandinavia, Poland, the Baltic region, and, finally, further into the Czech Republic and the Alpine region.
The extreme, prolonged, and excessive heatwave will engulf two-thirds of Europe.
Therefore, daily highs will continue to reach the low to mid-40s across France and Iberia, and by the weekend into early next week, also across parts of the Balkans and Italy.
Temperatures exceeding 40 °C on a daily basis for France, the UK, Benelux, Italy, and the Alpine region as excessive heat develops
With the strengthening ridge aloft and an associated warm plume, temperatures have already climbed significantly across Iberia and southwestern France.
France, Benelux and western Germany
Since last Sunday, the excessive heat wave has already spread over France, with peak daytime temperatures reaching into the 39-42 °C. And those will be even higher over the coming days. These temperatures will therefore challenge the historical records of hundreds of weather stations across France.
Some weather models hint at brutal heat on Tuesday and Wednesday, with peak afternoon temperatures potentially reaching 43-45 °C across much of central, northern, western, and southwestern France. This is truly historic heat, and even some all-time records may be challenged this week, not only obliterating June heat records.
The highest temperatures over western Germany and Benelux should reach the upper 30s, possibly 40-41 °C in some areas, from Tuesday through Thursday.
Ireland and the UK
Both the global and the high-resolution ICON/ARPEGE models are still suggesting that the 40-41 °C becomes increasingly likely, relatively widely across southern England on Thursday. This prompts a rare, red alert warning with extreme heat risk.
This is an extreme and yet again unprecedented heatwave that has developed in the British Isles. Numerous station records are challenged and might be broken, which is what literally obliterated June’s heat record across much of England and Wales.
Temperatures will also reach the low 30s across Ireland, Northern Ireland, and northern England on Wednesday and Thursday. Even Scotland is likely to see some 30s recorded in the valleys.
This is truly historic for so early in the summer season; the heat dome will be extreme.
Iberian Peninsula, Spain, and Portugal
Temperatures, with locally up to 44 °C, will develop from Tuesday through Wednesday across southern Spain, but will remain in the upper 30s at most over Portugal.
After midweek, temperatures will be slightly lower over the peninsula at least.
Italy and the central Balkan peninsula
Temperatures will also gradually rise across central Europe and the Mediterranean towards the following weekend, with the upper-30s to low 40s from Sunday through Tuesday next week across the North Italian plains.
It will also become much warmer across the Balkans, where temperatures will gradually rise day by day, reaching the upper 30s in some regions, with a dry air mass trapped beneath the expanding heat dome.
The overall weather pattern suggests that the excessive heatwave effect is likely to persist into early July, so the accumulating heat will be long-lasting, worsening drought conditions and gradually increasing the risk of wildfires. The soil is already quite dry in many areas.
We are closely monitoring the ongoing development of this truly historic Heat Dome and an associated excessive heatwave for Europe. We will update the forecasts accordingly as the situation evolves towards the next weekend. Stay tuned.
Stay tuned for the updates.
Windy, Pivotal Weather, and WXcharts provided images used in this article.
See also:
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