The first significant heatwave of summer 2024 is forecast for Europe

The first month of meteorological summer 2024 started with wet and cool weather across much of Europe; the only region receiving more summertime-like weather was recently far southeast Europe. The general pattern over Europe is finally changing to stop the rain events, but it will trigger excessive heatwave in south, central, and eastern Europe.

Temperatures are forecast to climb into the mid to upper 30s across many countries and could potentially challenge the 40 °C mark for the first time this summer this far north. The most anomalous temperatures are forecast for central Europe and the Balkan peninsula.

This pattern will expand across Europe towards midweek, while the blocking high will gradually shift east towards the weekend. Then, a progressive trough will follow into western Europe and could increase the likelihood of severe weather again.

This month’s weather picture over Europe was pretty much below the average, thanks to nonstop weather systems and rainy periods, including flooding events (e.g., Germany). However, one exception was across the far southern Balkans and southeast Europe. Extremely hot temperatures spread across Greece and Turkey.

The image below shows the maximum temperature on Thursday, June 13th. It reveals typical weather that has lasted almost since the beginning of the month: hot weather in southeast Europe but pretty cool weather elsewhere.

Therefore, June 2024’s first half will be below average across most of the continent, but conditions will improve as we head into the second half of the month with a more stable and much warmer weather forecast.

Temperatures in Greece and Turkey have been astonishingly high, even record-breaking for parts of Greece and the Aegean Sea. At nighttime, the temperature was in the mid-30s, peaking into the low to mid-40s during the day.

34 weather stations had maximum temperature above +42 °C, 136 stations above +40 °C and 322 stations above +35°C in Greece on the peak day, June 13th.

On June 13th, +44.0 °C was recorded in Milos, Greece, and +43.6 °C Rhodes. +43.9 °C was recorded in Kranidi, Crete. +45.3 °C was reported in Astromeritis, Cyprus. This was the hottest June day on record across the Southern Aegean Sea and the Rhodes Islands.

With Tmin of +28.2 °C, Aleppo, Syria had the hottest June night on record. It is even more impressive in Turkey, with Kas reporting a minimum night temperature of +33.0 °C.

It was extremely hot also farther south from Algeria and Libya to the Middle East, including Turkey. +45.7 °C was recorded in Mansion, Turkey, +45.5 °C in Karpuzlu with monthly records shattered in Aydin, +44.6 °C Manisa +43.4 °C and Izmir with +41.3 °C.

I-n-Salah, Algeria, recorded a minimum temperature of +34.9 °C and a peak daytime of +48.3 °C. The hottest night in history was reported from Benghazi, Libya, where the minimum temperature was +32.3 °C.

This week, temperatures are forecast to reach the mid-to-upper 30s across central Europe, the Balkans, and eastern Europe, with peak days possibly pushing into the 40s. Further west and north, temperatures will remain near or below average for mid-June.

The main reason behind the upcoming warm wave is a stable pattern aloft, known as the heat dome. Generally, when a long period of stable weather is established, this well-known feature intensifies a heatwave underneath.

What is a Heat dome, and why does it bring excessive temperatures?

The Heat Dome is the primary background feature that causes major heat waves globally every year. Last summer, there were particularly strong heatwave events, which continued into September and October. There have been thousands of record-breaking stations, and the temperature anomalies have often been off the charts.

On a global scale, temperatures from January through June have been well above the long-term averages. This anomaly has been so significant over the last 12 months that the chart below, provided by CopernicusEU, undoubtedly speaks for itself.

The Heat Dome is that feature that leads to these extreme heat events. Usually, the heat dome is the main and the most dominant feature of summer weather patterns in Europe and North America. Still, it can also occur in autumn, as we are experiencing this year.

We hear the term heat dome when extremely high and anomalous temperatures develop. Here is how it works and why it is important to understand it from a larger scale. The upper-level ridge pattern, or warm air mass in the higher altitudes, is known as the Upper High (we often use the term blocking High). It usually forms the heat dome.

So, this specific term is used when a broad area of high-pressure parks over a large portion of the continent. If the event is particularly stable and extreme, it usually stays there for several days or weeks.

The heat dome works like a lid on a pot. The extensive dome of heat traps a significantly warmer air mass at all levels underneath, sinking its layers toward the ground. Therefore, the air mass becomes dry and significantly warms as it reaches the lowest elevations.

A heat wave associated with a heat dome creates fair, stable weather and an often arid air mass with minimal chances for precipitation or even clouds. This happens due to the sinking air parcels in the center of the heat dome, resulting in rising temperatures. Sometimes, we see the weather pattern developing a so-called Omega blocking High.

The example below shows this kind of omega-blocking pattern over Europe from early September last year. The pattern engulfed a large part of the continent, with a central heat dome and a low-pressure system on each side. One low was over the southern Mediterranean, and the other over the Azores.

Especially during dry summer, drier and warmer weather produces a significantly enhanced wildfire threat due to developing drought. Or additionally worsening the ongoing, pre-existing, arid conditions. Such examples were wildfires in the Pacific Northwest and other parts of western North America in recent years or in Europe (Greece, Portugal, etc.) during last year’s summer season.

A heat dome is often also to blame for deadly heatwaves worldwide, as the scorching and excessive heat usually lasts for a very long period. Such heat dome events brought record temperatures in many countries worldwide in the summer of 2023, extending into the fall seasons.

The daily average and maximum temperatures under the heat dome are typically significantly above average. When the heat dome is particularly strong, it challenges existing historical records, as we have seen globally this year. This becomes particularly striking when this feature develops during early summer or autumn.

The first significant heatwave of summer 2024 develops into central and eastern Europe

As we head into mid-June, the general weather situation in Europe indicates a flip into more stable but significantly warmer conditions. With a heat dome strengthening and expanding from the Mediterranean region into central and eastern Europe, the air mass will be much warmer than earlier this month.

The ridge parks over central Europe and the Balkan peninsula, paired with a deep upper low over the Iberian peninsula and a shallow, weakening low over the eastern Mediterranean, establishing an Omega blocking pattern.

A southerly flow will establish a significant warm plume underneath the heat dome, achieving a much warmer air mass gradually spreading north from northern Africa across the Mediterranean to central and eastern Europe through early and mid-this week.

The first significant heatwave of the meteorological summer of 2024 will develop from Tuesday through Saturday. It will bring anomalous warm air mass to a large part of the European continent, with the hottest air mass from Italy to the central Balkans, Germany, Czechia, Slovakia, Hungary, and Poland from Wednesday through Friday.

The following 2m temperature anomaly chart indicates how much warmer temperatures will be during the peak daytime hours on Wednesday (left) and Thursday (right chart). While the Alpine region and Germany get the warmest air on Thursday, Friday peaks the heatwave across Italy, the northern Balkan peninsula countries, Czechia, Slovakia, Hungary, and Poland.

Afternoon temperatures will be much above the average for this period, locally even more than 10 °C above.

Here is a video animation of the whole heatwave and its progress across portions of Europe this coming week. Throughout the second half of the week, we can see the development of an Omega pattern and significantly warmer air mass underneath.

Although the heatwave will not last long (for now), the air mass will warm up quite dramatically compared to the conditions Europe has experienced so far this month.

The frontal system’s effect of keeping colder air mass over Western Europe will create a sharp temperature contrast against Central Europe. Strong upper-level winds will establish between these two large-scale features, thus supporting more unstable weather—we will discuss potential impacts further down.

Temperatures will push into the upper 30s across broad regions. They could challenge Italy’s first >40 °C mark this year

As the upper High gradually expands from the Mediterranean into central Europe and the Balkan peninsula around mid-week, temperatures will warm up significantly across Italy, Germany, Croatia, Slovenia, Hungary, Czechia, and Slovakia.

From Wednesday through Friday, peak afternoon temperatures are forecast to reach the mid-30s, with each day warmer towards the heatwave peak on Friday.

The chart below represents the peak temperatures across Italy and the Mediterranean on Thursday and Friday. We can see that temperatures will climb into mid-30s across central and southern Italy on Wednesday, gradually increasing through Thursday and Friday. Friday should bring the highest temperatures for this heatwave. The maximum temperatures will reach around 33-35 °C across the north.

It will be much warmer over central Italy, where the core of the warmer air mass aloft will be. There is a high potential that temperatures will reach around 40 °C or surpass on Friday, so up to +42 °C will be possible. Similar conditions are also present across Sardegna Island and the upper 30s across south Italy.

Very hot weather is also expected across the northern Balkans countries on Thursday and Friday, with the highest temperatures approaching 40 °C over Croatia. The surrounding region will also experience temperatures into the upper 30s on both days.

The highest temperatures are forecast on Thursday on the northern side of the Alps, with 30-33 °C across the southern half of Germany, eastern France, and Austria. Elsewhere, temperatures will be in the upper 20s.

Friday (right chart) will already bring some refreshment with the frontal system from the west while the heatwave peaks across eastern Germany, Czechia, and Poland. Low to mid-30s are forecast over this region.

Although the Omega blocking pattern will be centered across central Europe and the northern Balkans, the heatwave will also re-intensify in the southern portions of the peninsula. After Wednesday, temperatures will rise above 35 °C across Greece, North Macedonia, and Bulgaria.

The highest temperatures across the southern Balkan peninsula countries are forecast for Thursday, with some valleys approaching the 40 °C mark again, but far from the scorching heat experienced last week.

Next weekend, refreshments will be brought from the west, and temperatures will return to normal values for June, peaking from the upper 20s to the low 30s.

Note: There are some hints that the heatwave will begin intensifying again at the end of June.

A progressive pattern follows into west-southwest Europe behind the heatwave

While the Omega blocking pattern engulfs central and eastern Europe, a deep trough will emerge across the Bay of Biscay and the Iberian peninsula after Wednesday. This generally means an increasing chance for more dynamic weather since moisture returns northwards from the Mediterranean.

Therefore, significant instability builds up ahead of the frontal system and trough from the west. Mid-term trends suggest that parts of western and southwestern Europe, from Spain across France to Switzerland, Germany, and Poland, will see severe storms return from Wednesday through Friday.

This is also when the heatwave peak further east will occur across central and eastern Europe, around Thursday or Friday. Meanwhile, the trough from the Atlantic will bring much colder weather into the Iberian peninsula.

In the second half of the week, Portugal and Spain will experience colder-than-normal weather behind the frontal system.

Severe storm potential will increase from Spain to southern France by Wednesday afternoon as a deep trough emerges from the Bay of Biscay. Then, the upper-level disturbance with a surface frontal system will be dragged northeast towards Benelux and the North Sea through Friday.

Therefore, changes for severe weather will increase across France, Switzerland, Benelux, and Germany on Thursday, with more storms along the moving frontal boundary further east a day after. On Friday, the moving frontal system will bring severe thunderstorms to Germany, Austria, Czechia, and Poland.

Given the warm wave coming up through mid-week, the air mass will warm up ahead of the front and combine with a strong jet stream aloft, supporting severe thunderstorms capable of producing severe winds, large hail, heavy rain, and tornadoes.

The Health Risks During A Heatwave

During an extended period of very warm weather, generally surpassing +35 °C, it is physically challenging and presents an enhanced risk for health.

Sweltering weather, particularly in extended periods – heat waves – is uncomfortable but presents a significant health risk.

Who is most at risk?

Scorching hot weather is uncomfortable for most people. The following groups are particularly threatened by the very high temperatures we encounter during heat waves:

• elderly people aged over 75 years
• babies, young children
• people with chronic/long-term health conditions, such as diabetes, respiratory disease, circulatory disease
• People who are obese
• People taking certain medicines
• people who work outdoors, in hot/poorly ventilated areas, or engage in physical activity in hot weather
• socially isolated people
• people who are not acclimatized to hot weather, such as tourists from northern countries

Always stay cool, hydrated, and healthy in scorching hot weather

Staying hydrated is one of the most crucial things during extreme heat. Consider taking these precautions and measures to stay healthy in scorching weather:

• Drink plenty of water! – A human’s body cools through sweating; on a sweltering day, an adult may lose up to several liters of water. Keep drinking water, and avoid drinking alcohol, hot drinks, and drinks with high sugar content, as they can worsen dehydration. Regular water intake is a good way of preventing dehydration.
• Keep your body cool; stay out of the sun if possible. Eat small meals, preferably fruit, and salads. Wear light-colored and loose clothing made from natural materials like cotton. Take a cool shower or a cold bath if you feel hot. Also – keep your workspace and living space cool. If you do not have air conditioning, shut the curtains and blinds during the day. Stay in the coolest room, and avoid using the stove and oven as much as possible. If your home gets too hot, go to a cooler place – a library, shopping center, cinema, or swimming pool.

• Keep your food safe! Properly Store food that needs refrigeration! Food spoils rapidly at high temperatures, and you may risk food poisoning if it is not stored correctly.

• If you need to go out in the sun, protect your skin, use proper sunscreen and clothing to avoid sunburns and cover your head correctly.

• Know your body and have a plan – Ask your doctor if you have any health conditions that may increase the risk of heat-related illness. Call and consult with your doctor if you are feeling unwell. Call emergency help (know the number!) if you feel unwell!

Common heat-related illnesses with symptoms: What to do if it happens?

WHO considers these symptoms’ descriptions and treatments below as informative only – consult with your doctor for details and professional advice:

Dehydration
 

Dehydration occurs when the body loses too much water to maintain normal functions. Symptoms include dizziness, tiredness, irritability, thirst, dark yellow urine, loss of appetite, and fainting. Drink plenty of water or diluted fruit juice. Avoid coffee, alcohol, and sugary drinks. Move to a cooler space to cool off. If you feel unwell, call your doctor or emergency room.

Heat rash
 

Heat rash is an itchy rash caused by excessive sweating. Move to a cooler, dryer environment, and keep the affected areas dry. Hydrating creams may make the condition worse. Consult with your doctor.

Heat cramps
 

This happens during strenuous activity when the body sweats and loses water and salt. Heat cramps manifest as muscle pains or spasms. If this happens, stop all activity, move/lie down in a cool place, and raise your legs slightly. Drink water or diluted juice. Have a cool shower or bath, and apply ice packs. Refrain from returning to strenuous activity for several hours. If heat cramps do not subside, seek medical help.

Heat exhaustion
 

Heat exhaustion is a condition caused by dehydration, which causes excessive loss of water and salt. Symptoms include heavy sweating, pale skin, fast and weak pulse, fast and shallow breathing, muscle weakness or cramps, tiredness and weakness, dizziness, headache, nausea or vomiting, and fainting.

If heat exhaustion occurs, the body needs to be cooled and rehydrated by moving to a chilled place, lying down, having a cool shower or bath, and placing cool packs under the armpits, groin, or back of the neck. Rehydration should be done by taking small amounts of cool fluids. Medical help is advised if symptoms do not abate within an hour.

Heat stroke
 

Heat stroke happens when the body temperature reaches 40.5 °C, a severe and life-threatening condition! Immediate first aid in lowering body temperature is critical, and an immediate call for an ambulance! Find more information on heatstroke here.

High relative humidity during a heatwave can also significantly affect the body, making it physically challenging for those working outside. After high rainfall, intense heating helps evaporate the soaked grounds, resulting in higher humidity than normal.

We use a heat index to represent the real feel of scorching hot temperatures and high humidity. These graphics indicate the real feel of temperatures based on the temperature and humidity.

As we see, when air mass has a temperature around +35 °C, humidity below 60 percent is much less challenging than once the humidity is very high, e.g., above 80 %. Thus, the real feel temperature would be near 50 degrees Celsius.

Even at temperatures close to the 40s, such sweltering hot air becomes hard to handle with even lower humidity, 50 to 60 percent.

Wxcharts, Pivotalweather, ClimateBook, and Meteociel, provided images for use in this article.

See also:

June 2024 Weather Forecast: Europe’s weekly Weather trends