While July continued with heatwaves across south and eastern Europe, the heat is finally spreading towards western Europe as well. Most of Western Europe will face a short but intense heatwave as the Olympic Games 2024 kick-off. A warm plume of air mass will spread temperatures exceeding the +40 °C threshold across parts of France and close to +45 °C in Spain again.
According to the forecasts of the global weather models, temperatures throughout the final days of July will be much above average across Southern and especially Western Europe. The most anomalous hot temperatures are forecast across France, Benelux, and the Iberian peninsula early next week.
Through mid-July, the general pattern over Europe shifted into a stable one, inducing a prolonged heatwave across the southern portion of the continent. Temperatures broke records across Southern and Eastern Europe, with long-lasting heat and especially extremely warm nights. Those finally got lower this week.
However, the heatwave intensified from Western Sahara into the Iberian peninsula. Morocco and Algeria broke several daytime high and nighttime low-temperature records, and Spain and Portugal peaked past +45 °C mid-this week.
On Wednesday, July 24th, up to +42 °C was recorded in the Spanish capital Madrid community (Aranjuez) and +42.3 °C at the Ciudad Universitaria area. It was much warmer across southern and southwestern Spain, including southern Portugal. El Granado, Spain, reported +45.6 °C on Wednesday. Alvega, Portugal, was slightly lower; the maximum temperature ended at +45.5 °C.
A record-high minimum temperature was recorded in Portalegre, Portugal; nighttime temperatures couldn’t go lower than +28.6 °C.
In North Africa, scorching heat is normal in July, but this was also a historic event. Tindouf, Algeria, recorded a minimum temperature of +35.6 °C, the highest ever for the station. The daytime maximum was +48 °C there. Marocco smashed a few all-time station records, Kasba Tadla ended at +48.3 °C, and Beni Mallal tied its record with +47.7 °C.
This weather pattern will continue across southern Europe through the remainder of July and extend into early August. At the same time, a gradual spread of hot weather will follow up after Sunday, peaking over France during the first week of the Olympic games.
A blocking high – the upper ridge – will strengthen from the western Mediterranean region into France and Benelux, also reaching the UK, thanks to a heat dome establishing aloft.
What is a Heat dome, and why does it bring long-lasting heatwaves and excessive temperatures?
The Heat Dome is generally the primary background feature that causes yearly intense heat waves. During the summer of 2023, there were extreme 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.
Similar events occurred across the Balkan peninsula and Eastern Europe through mid-July this year.
Heat waves are again breaking records this summer, and their longevity and nighttime lows are especially astonishing. Also, on the global scale, July 21st set the new world record for the daily global surface air temperature. It was 17.09 °C, breaking the old record by 0.01 °C from July 6th, 2023.
Global temperatures from January through July this year have exceeded the long-term averages. This anomaly has been so significant over the last 12 months that the chart 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 last year.
We hear the term heat dome when extremely high and anomalous temperatures develop. Here is how it works and why it is essential 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 exceptionally 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, minimum, and maximum temperatures under the heat dome are typically significantly above average. When the heat dome is solid, it challenges existing historical records. This becomes particularly striking when this feature develops during early summer or autumn.
A strong upper ridge strengthens across Iberia into Western Europe. Heatwave intensifies beneath
Thanks to a strengthening heat dome and blocking high aloft, the high-pressure system will build up across Western Europe this weekend and early next week. The warm plume above will allow the heatwave to intensify over Spain and Portugal into France, Benelux, western Germany, and the UK.
The upper-level ridge is forecast to be the strongest through the early days next week, pushing temperatures in the lowest levels into the mid-30s across central France, including the capital, Paris, where the Olympics are ongoing.
The highest temperature anomaly is expected across France, western Germany, Benelux, and the southern UK through Monday and Tuesday. Temperatures will be around 8-12 °C above the average for the end of July.
The strengthening heatwave will allow temperatures to climb the most across parts of central France, with the upper 30s likely on Monday and Tuesday. Above 40s are forecast across the south.
The following chart indicates the 2 m temperature anomaly on Tuesday this week, with abundant heat underneath the heat dome and ridge aloft.
After Wednesday, the hottest air mass will gradually diminish as a more dynamic weather pattern will likely develop in Western Europe again. Mid-term weather models indicate a deep trough may develop over the Atlantic, with frontal systems spreading into the UK, France, and Benelux late next weekend.
However, the blocking ridge aloft will likely remain further south towards the weekend, so the heat will continue across most of Southern and Central Europe.
The general temperature picture hints at the summer heat continuing to dominate the southern half of Europe through early August. According to global GFS and ECMWF weather models, it may extend further towards mid-month.
Below is a video animation of the heatwave’s redevelopment across Europe and its progress across Western Europe next week.
After mid-week, the overall weather model consensus also suggests that chances for rain and thunderstorms (including severe storms) will again be possible across western Europe. Meanwhile, the South and East remain more stable, hot, and dry.
Heatwave pushes temperatures into the mid to upper-30s across central France; The low-40s across southern Europe
With the upper High gradually expanding and strengthening from the Mediterranean into Western Europe next week, temperatures will warm up again from Portugal and Spain and spread into France, Germany, Benelux, and the UK. They will also increase across Italy, the Balkan peninsula, and central Europe.
France, Benelux
From Sunday through Tuesday, peak afternoon temperatures are forecast to reach the mid-to upper-30s across central and southern France. On Monday and Tuesday, temperatures are forecast to reach the low 40s across southern France.
The highest temperatures on Tuesday could reach around +42 °C across the lowlands of southern France. The drier air mass and the southerly winds off the Pyrenees normally push temperatures very high there.
In the French capital, Paris, a region where the Olympics are ongoing, temperatures are forecast to reach 32 to 36 °C from Monday through Wednesday.
Spain and Portugal
After a temporal relief across Portugal and Spain since Wednesday, temperatures are forecast to climb back into scorching heat after Sunday. It appears likely that multiple consecutive days will bring temperatures into the 40-43 °C range across the southern half of Spain.
The heatwave will also re-intensify across Portugal, bringing temperatures back into the upper 30s across most of the country. Some areas will likely get back to the 40s on some days next week.
After Monday, the heat-prone lowland regions of southern Spain are likely to experience temperatures close to +45 °C again.
The UK and Ireland
The summer heat will finally reach the UK and Ireland next week. The heatwaves have been lacking across Western Europe this summer. But as July ends, at least a few very warm will spread across the region.
Daytime temperatures are forecast to reach the upper 20s to low 30s across southern England on Monday through Wednesday. The mid-20s are forecast across central and northern England and Wales. Further north into Scotland, low 20s are forecast for at least a few days.
Low 20s are also forecast for Ireland and Northern Ireland next week, mainly Monday through Wednesday.
Italy and the Balkans
The heatwave across the Mediterranean and Balkan peninsula is expected to continue through the remainder of July and extend into early August.
The forecast peak temperatures from Sunday through Friday next week suggest that parts of Italy, the south-central Balkans, and the Panonian plains will experience upper 30s to low 40s temperatures.
No significant temperature changes are foreseen across the southern half of Europe further into August. Therefore, a heat wave may extend into mid-August.
The Health Risks During A Heatwave
During an extended period of hot 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 usual.
We use a heat index to represent the natural feel of scorching hot temperatures and high humidity. These graphics indicate the natural 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 actual 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 this article.
See also:
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