Being abroad in Great Britain I was fortunate to witness the hottest summer, that ever occurred in the British Isles. Because I am from Poland, in this article I would like at least a bit to compare last British Summer with the Polish one and say a little bit about this summer in general, referring to the whole northern hemisphere. I am very surprised, that this year I could experience a hotter Summer, than in Poland and the rest part of Central Europe.
The hottest summer came after a relatively cold spring. Because in the first part of the year temperatures across the UK were much lower than in previous years I didn’t suppose, that summer would come at all. A few “beasts front the east” stroke the British Isles between February and April, causing lag in sprouting and vegetation development. The situation changed in mid-April when temperatures shot up to about 25 degrees Celsius for a few days and the next, aftercooler period, around the May Day bank holiday. Despite late spring approaching May was the warmest and the sunniest, as recorded in the UK.
The hottest summer approached suddenly. It comprised about 5 heatwaves between 23 June and 21 September, although as far as I have noticed English meteorologists used to say “heatwave” already when the temperature hovers around 25 degrees Celsius. Possibly this is because of the high humidity, which is typical for maritime climes, making a feeling temperature higher than it really is.
Anyway, I will associate this summer with a vast five-week heatwave, that resulted in a huge drought across the country and, what is irritating, terminated a few hours before the total lunar eclipse.
1. UNUSUALLY HOT WEATHER IN GREAT BRITAIN
The summer in Britain began on the 22nd of June when a heatwave was officially declared in Scotland and Northern Ireland. The temperature there rose above 30 degrees Celsius, which was not observed since 2003. In other parts of the country, the heatwave began on 23rd June. After a few days, intense hot wildfires were reported. The two largest wildfires at Saddleworth Moor broke out on 25 June and they were the largest wildfires in England’s living memory.
Other wildfires were observed in Wales (Ceredigio) and at least a few different places. Another reason for wildfires, next to the heat was a breeze, that occurred along with hot weather. Due to this the vegetation and underlying peat had been dried out quickly, becoming easy to burn.
The late June heatwave set the highest temperatures in the milder parts of the UK: about 32° in Wales (Porthmadog), 31° in Scotland (Aviemore, Glasgow), and 30 deg in northern England (Carlisle, Keswick) and Northern Ireland (Edenfel). Along with the heat, many hours of sunshine were recorded across the country.
In early July some cold front entered the British Isles but stopped over Ireland and the Irish Sea. In the result above the Pennines, Caledonian, and Cambrian Mountains heavy downpours and thunderstorms occurred occasionally. The weather in another part of Great Britain was mostly sunny, hot, and dry. The continuation of the high temperature resulted in such unusual things as tarmac melting in many places of the eastern UK. The asphalt concrete softening caused freak events; a bin lorry’s back wheels sank into the road in Newbury. In another part of the country, a man’s leg sank into a melted road near Newcastle. Mid-July was a bit cooler but still dry and sunny. Only a few hefty rainfalls passed in places across England and Wales, whereas Scotland and Ireland faced more wet and colder weather.
The next serious heatwave, which set the highest temperatures in southern and central England came in late July.
The highest temperature values were recorded in Kent and Norfolk (35 degrees of Celsius). The extremely long dry and hot spell has been broken by a cold front sweeping from the west.
The next day temperature dropped rapidly and the weather changed in general, bringing the first serious rainfall in eastern UK regions. Hot weather returned in early August, however, it lasted shortly, only 3 days. The temperature record wasn’t beaten, but thermometers reached serious values accordingly: 33° in London, 32° in Norwich, and 31° in Cambridge. Quite a high temperature was recorded at that time in Wales (28° in the Powys region), Scotland (27° at Lossiemouth), and Northern Ireland (24° at Helens Bay). By the end, the first decade of August British summer became cooler with some misty weather in places. The end of August was really cold, especially in Welsh and Scottish mountainous areas, where in places even ground frosts were reported (Harmon in Powys, -0.2°, Braemar in Aberdeenshire -1,3°). The warmest remained southeast part of England with a daily temperature between 20 and 25 degrees of Celsius.
September continued warm and mostly sunny weather in Britain. In the southeastern part of England, the temperature was about 25 degrees Celsius (26 degrees in Cambridge). The first days of September were also warm in Wales, where temperatures also reached 25° (Hawarden in Clwyd), Scotland (26 deg at Lossiemouth in Maryshire), and Ireland (22° Londonderry, 23° Dublin). However warm weather didn’t last long in the western UK and Ireland. After 3 days northerly outbreaks brought much cooler weather with some ground frosts recorded under clear sky conditions in Scotland (-2.5° at Braemar in Aberdeenshire) and a lot of sunny days at once.
The last warm wave was observed before the end of the 2nd decade of September, which marked the end of the summer. In the southeastern part of the British Isles, the temperature reached 26 degrees of Celsius again (Cambridge), however, this warm weather didn’t spread outside the English lowlands. In Wales, Ireland and Scotland’s weather was quite cool and unpredictable. Around 20th September a storm season began in most parts of the UK. The first storm Helene brought very windy conditions to Ireland and many parts of the western UK. Next storm Ali approached 2 days later and featured much more windy conditions, defeating a warm air mass from British Land on the 21st. The 21st of September marks definitely the end of the summer then.
Concluding a whole scenario described above the period of most severe hot weather occurred between 22nd June and 27th July, without any precipitation, at least in Cambridge. The long period of dry hot weather, usually without an unpleasant level of humidity caused one of the biggest droughts in UK history. It was the biggest drought since 1976. In effect, in many regions of Great Britain and Ireland, a hosepipe ban was introduced. The long heatwave changed the scene a lot. In every parkland and garden squares were turned into brownish, sunbaked, and parched areas.
This drought has been saved not only in pictures and satellite imagery but also in the main climate graphs (mean temperature anomaly and precipitation).
2. WEIRD SUMMER IN EUROPE AGAINST NORTHERN HEMISPHERE
The extremely hot weather was reported in many regions of the northern hemisphere from North America to North Asia. In western Canada, the temperature reached 40 degrees Celsius in August. In many places, a new heat record has been set. In Quebec and Ontario, temperatures rose up to 35 degrees of Celsius. We must be aware, that in terms of the humidity, the humidex values could be much higher! A much stronger heat wave touched the western USA, where temperature skyrocketed to 47 degrees of Celsius near Los Angeles and even 51 deg in Death Valley. Extremely high temperatures occurred also in Mexico, where the Chihuahua region was between 45 and 50 degrees of Celsius. The North American heatwave caused a lot of wildfires and deaths. A record-breaking heatwave affected also Japan, Korea, and China, where the temperature hovered about 40 degrees Celsius. In effect, at least 200 people died from heat-related causes. Another over 70000 required hospitalization.
In the Middle East, in Oman, the highest “low” temperature in known history has been recorded. On 26th June the low temperature was almost 43 degrees of Celsius! At Quriyat.
The hot weather didn’t miss Europe, however, higher temperatures than normal were not observed on the whole continent. On top of that heat waves didn’t hit a whole continent at once. Whilst in some regions an unusual hot was reported, in other parts of the continent people were struggling with weather not adequate for location and part of the year. For instance, when the United Kingdom was facing a historic heatwave, the Dalmatian coast experienced huge and quite often cold outbreaks with severe thunderstorms.
In general, June 2018 has been remembered as one of the wettest June in southeastern Europe. Rain, thunderstorms, and flooding occurred especially in Greece and southern Italy. At the same time, a considerable drought occurred in the Baltic and the North Sea regions.
Early July brought an extremely low temperature in central and eastern Europe. The maximum temperature recorded in Belarus and north-eastern Poland was one of the lowest observed in known history. In places, the maximum temperature didn’t even reach 12 degrees Celsius! The lowest maximum values of temperature were observed in Bialowieza (about 11°), Baranovici (11°), and Pinsk (11° ).
The low-pressure area presence with cloudiness prevented this region from ground frosts, which occurred more westwards in Poland. The lowest ground temperature has been recorded in Jakuszyce (-4°, Wierzchowo -1.5°, and Swieradow-Sudow -0.5°). In Jakuszyce frost was reported even at 2m above ground (-1.5 degrees of Celsius).
For most of July in Poland, especially in the southern mountainous part of the country was raining causing flooding, which is nothing unusual this month.
Heatwaves started to hit Poland seriously by the end of July. Earlier hot weather reached the northernmost part of Europe, where more than 30 degrees of Celsius have been reported. On the Barents Sea coast, in Makkaur Fyr temperature reached a score value – 31 degrees of Celsius! On the coast inside the polar circle at almost 71 north latitude!
Another of the highest temperatures in known history as recorded in the Arctic Circle was reported in Utsjoki (Finland) at 33° and Banak Penninsula (Norway) at 32°. In many places across the continent, the temperature values have not been seen for at least tens of years.
This serious heatwave, lingering nearly 2 weeks above Scandinavia caused a lot of wildfires, observed mainly in Sweden, which was the most affected by hot weather. The Swedish firefighters were not prepared for such a large-scale wildfire event. Then 140 Polish firemen, as well as teams from different European countries, came to help them to put out forest fires.
An extreme heat wave engulfed also the southern and southwestern parts of Europe, especially in Greece, where 92 people died because of wildfires.
Another heatwave stroke on the Iberian Peninsula between 25th July and 5th August. As a result, about 23 people in Catalonia died. In Portugal and southern Spain, the temperature reached 46 degrees of Celsius on August 4th. The hot weather in southern Europe as well as in Scandinavia continued in August. As the result of a 3-week hot spell in Sweden, the highest peak of the country – the southern summit of the Kebnekaise Mt. melted down, losing its privilege eventually.
In Poland, the weather improved by the end of July, and early August brought a serious heat wave with max temperatures of about 35 degrees of Celsius. Next to very hot days, the temperature was high during the height also. The hottest night was between the 9th and 10th of August when in most of the country temperature didn’t fall below 20 deg. The highest low temperatures were measured in Bielsko Biała (25°), Cieszyn (24°), and Hel (23°).
In contrast to 1st part of August, the late period of this month was much colder. When this cold spell emerged for a while, then very low temperatures during the night were reported. Due to polar marine air mass, an overnight temperature fell to around 5-7 degrees, whereas near the ground only 1-3 degrees of Celcius were reported. After this cool impact, the hot tropical air masses came again, bringing hot temperatures in central and western Europe for the first two decades of September. The temperatures reached about 31 degrees in Poland, 33 degrees in Germany, and even 35 degrees in France.
The dry and hot spell continued until September 21st, when serious storms from the Atlantic Ocean entered the continent, reducing the temperature by about 10-15 degrees.
It was definitely the longest and the hottest summer ever seen in Poland and one of the warmest in western Europe. I wrote Western because higher temperatures than normal were not observed on a whole continent.
Undeniably the most affected were the southern and western parts of the continent with the British Isles. Surprisingly also on the Scandinavian Peninsula has also been strongly affected by heat. The biggest positive land surface temperature anomalies have been reported for Great Britain and Ireland (up to +8 degrees of Celsius in places), Norway (up to +8 degrees in mountainous areas), Denmark and Sweden (between +4 and +6), Benelux (about +3 degrees) and Portugal (between +2 to 3 degrees). The biggest anomalies have been reported for mountainous and marine areas, where hot weather happens very rarely. In those areas, a heatwave caused many destructions and landscape changes due to massive snow and glacier disappearance. The most known situation comes from Sweden, where the highest peak of this country – the southern tip of Kebnekaise, has been shrunk by about 4 meters. The glacier enshrouding the top of a mountain melted down within 1 month. Aside from many heat strikes throughout the whole summer, there were other unusual weather situations, which made this summer quite weird. In the eastern part of the continent, the land surface temperature anomaly was much below the average value. In eastern Belarus, the deviation reached from -6 to -8 degrees of Celsius. A relatively cool summer occurred also in southern Finland, Lietuva, Latvia, western Russia, and northern Ukraine. Even in the areas affected by heatwave, some colder and wetter periods were reported, like Balcanian countries in June.
3. ENVIRONMENTAL, ECONOMIC AND HEALTH EFFECTS OF THE HEATWAVE
Every heatwave generates environmental, economic, and health effects, which are dependent on the severity of the hot weather. I have gathered all the pros and cons of this kind of weather below based on all the information gathered from last summer’s heatwave in Europe, especially in Poland and the United Kingdom.
– Long hot weather results in increasing the temperature of the surface water in lakes and seas. For instance in Poland Baltic Sea at Pucka Bay had a surface water temperature reaching 26 degrees of Celsius, which is typical for the Mediterranean
– Heatwave causes drought and a very quick decrement in the climate water balance value, as we could observe in the case of the western and northern parts of Poland.
– Moreover, a soil structure changes during extremely long hot weather. The soil appears to look like a rock, completely cracked. I could see it in England, which is a very rare view in the country with the marine climate,
– The long period of drought results also in crop failures, where the biggest concerns refer to wheat and barley harvest. On top of that sometimes, like last summer in the UK, in many places grass intended for livestock grazing withered, so that dairy cattle had to be grazed on land intended to grow hay or silage for winter feed for the cows,
– The long heatwave changes the scene a lot. Last summer in England every parkland and garden square was turned into brownish, sunbaked, and parched areas.
– A heatwave strongly boosts the domestic tourism trade. Last summer, the number of international visitors to the UK increased significantly as well as domestic tourists. Many British tourists decided to spend the holiday in their own country.
– Hot weather causes a demand for outdoor activities stuff and fresh fruits highly increased,
– The hot spell causes higher electricity usage due to air condition demand. Finally increases the risk of a power cut, as usually happens in Poland,
– During the hot weather, employers have to cut down the employee’s work hours or arrange for them to have more cold water, extend a break time, etc. Workers lose their capacity, which cascades a negative effect on the whole business,
– Extremely hot weather results in a lot of infrastructural and architectural damage. A typical example is melting tarmac, however, sometimes even some building constructions may be affected by high temperatures. The best example is from Glasgow when the Glasgow Science Center roof melted during the extreme heatwave at the end of June,
– Hot weather can cause also a shortage of drinking water, which effect can result in a hosepipe ban,
– Drought always leads to an increase in food prices due to poor harvest.
A long lack of precipitation caused vegetation to reveal many curious historical objects and cultural heritages across the UK country thanks to crop marks painted into the landscape. A prehistoric or Roman farm has been discovered near Langstone in the Newport area. In another place, the 200 m diameter henge has been discovered from a drone perspective.
– People have the worst health conditions due to extremely long heatwaves. Hot weather causes cardiovascular diseases, heart attacks, and deaths. The worst situation is when hot weather is combined with high humidity. Then a person will be sweating, but sweat doesn’t be drying on the skin,
– Shorter exposure to severe heat may result in negative symptoms such as dizziness, headache, fainting,
– Long drought periods can deteriorate air quality, which contains more harmful aerosols,
– Recreational injuries can be quite common during hot weather because many more people want to have some summer fun in the water,
4. MAIN REASONS FOR EXTREMELY HOT WEATHER
This type of weather occurs during the summer, when a blocking anticyclone (often the Azores high), forces other low-pressure systems around it, usually to the northwest. This situation causes hot and dry weather for a long time in the southern part of the UK, whereas north and northwest regions of the country often receive above-average rainfall. A factor, that can decide about the strong high presence is sea surface temperature anomalies in the Atlantic. Basically, when the observed sea surface temperature is lower in the North Atlantic, then a warmer ocean temperature anomaly is observed south of the tropic of Cancer. This is a part of the Atlantic multidecadal oscillation, which incurs a different air circulation pattern in the atmosphere, which leads to the development of a heatwave across Europe. The ocean anomaly is linked to a stationary position of the Jet Stream that favors the development of high surface temperatures over Central Europe during the heatwave (Duchez et al., 2016). The jet stream – a core of strong winds around 10-13 km above Earth’s surface steers weather around the globe. When these winds are intense, they bring storms. On other occasions, when they are the week the calm weather occurs likewise during last summer. Because now the jet stream is extremely weak then atmospheric high-pressure systems are lingering for long periods over the same place. A weakening of the Jet Stream is caused by a decrement in the temperature difference between polar and lower latitudes, which I have described in this article. The last hot and dry spell in central and western Europe was a combination of both aforementioned factors and the climate change process, which led to an increment in the temperature around the Globe. This ongoing trend of warming cause also land surface and the atmospheric circulation system changes.
I have described the hottest summer in the British Isles and Europe. I put a lot of weather forecast maps, that in places could not reflect real weather patterns, because these maps were only predictions. However, the differences between forecast and real patterns were not so huge. Concluding this article I would like to say, that if somewhere is warmer than normal, in another place it must be colder. This is perfectly reflected on the surface temperature anomaly map for Europe, where the western part of the continent is much warmer than usual unlike to eastern part, which is colder. The main role in this scenario is the Jet stream, which is weakening due to global warming. The results we could see this summer, being recognized as the hottest one. A weak jet stream causes calm weather with lingering high-pressure areas, pushing the hot air far north for a long period of time. On the other hand in other parts of the continent, we could see a never-ending cold and rain. Moreover, an “omega” shape of the jet stream caused unusually bad weather in regions, where it should happen in the summertime. The best example was flooding in Greece and the Balkan Peninsula. The jet stream behavior brought such extreme weather patterns, not only a heatwave but also unusually low temperatures even with frost. It means, that in terms of weird weather caused by global warming, we should expect literally every kind of clime throughout the year on European latitudes. Next to extremely hot and dry spells, opposite weather with long-term rain, flood, or exceptionally low temperature occurs. The warming trend will cause similar, even worse weather patterns in the future for sure. There are a lot of things to work with for sure in order to protect the environment and human life.
- Duchez et al., 2016, Drivers of exceptionally cold North Atlantic Ocean temperatures and their link to the 2015 European heatwave, (in:) Environmental Research Letters, vol. 11 no.7
- Xia et al., 2018, Assessment of the economic impacts of heatwaves: A case study of Nanjing, China, (in:) Journal of cleaner production, vol. 171, p. 811-819
- Metoffice.gov.uk: 2018 UK weather summary
- Metoffice.gov.uk: May 2018 statistics
- Metoffice.gov.uk: End of summer – stats
- Metoffice.co.uk: Summer 2018 summary
- Meteomodel.pl: Kwiecien – wrzesien 2018 w Europie
- TheGuardian.comSummer 2018 UK the hottest on record Met Office says
- 27.06.2018: Dramatic aerial views of large gorse fire still raging in Northern Ireland
- Wunderground.com: Minimum temperature 42.6 degrees in Oman on 26th June – new World record
- 28.06.2018 Pressreader.com: Inferno on the moors
- 28.06.2018 Glasgowlive.co.uk: Glasgow science centre roof melting
- 28.06.2018: Netweather.tv: Intense heat for Scotland and Northern Ireland today than South Britain at the weekend
- 28.06.2018 Quiarat, Oman – the hottest low temperature ever seen
- 28.06.2018: This year’s UK heat record broken again in Porthmadog
- 2.07.2018: Meteomodel.pl: Rekordowo zimny dzien na polnocnym wschodzie Polski (Polish)
- Dobrapogoda24.pl: Początek lipca przyniósł lokalne przymrozki (Polish)
- 5.07.2018: Man gets stuck in melted tarmac in Newcastle
- 5.07.2018 Twojapogoda.pl: Jedna połowa Polski w suszy zaś druga w deszczu czeka nas spore przemeblowanie w pogodzie
- 7.07.2018 Bbc.co.uk: Heatwave unveils ancient settlements in Wales
- 11.07.2018 Rte.ie: Possible Meath archaeological discovery described as ‘very significant’
- 22.07.2018 Meteomodel.pl: Rekordowe lato w Skandynawii
- 18.07.2018 Meteomodel.pl: Silne opady pierwsze podtopienia (Polish)
- 19.07.2018 Meteomodel.pl: Ekstremalne temperatury w polnocnej Skandynawii (Polish)
- 20.07.2018 Pap.pl: Polish firemen will help to fight forest fires in Sweden
- 2.08.2018 Nytimes.com: The highest peak in Sweden has been melted down.
- 3.08.2018 Telegraph.co.uk: Firestorm the wildfires sweeping Europe and Britain
- 3.08.2018 Time.com: Swedish highest peak melted away during the last heatwave
- 10.08.2018 Meteomodel.pl: Ekstremalnie ciepla noc (Polish)
- 27.08.2018 Twojapogoda.pl: Wyjatkowo zimna noc i poranek – temperatura spadła przy gruncie nawet do 2 stopni
- 9.03.2018 Twojapogoda.pl: Woda w Bałtyku cieplejsza od tej na Kanarach, jest tylko jedno ale (Polish)
- 21.09.2018 Twojapogoda.pl: Dzisiaj kończy sie najdłuzsze i najgoretsze lato w dziejach polskiej meteorologii (Polish)
- 21.09.2018 Meteomodel.pl: Koniec lata
- The role of the Atlantic Ocean in the UK Heatwave
- The omega-shaped jet stream responsible for Europe’s heatwave
- The Guardian: The big heatwave: from Algeria to the Arctic. But what’s the cause?
- Walesonline.co.uk: What caused the UK heatwave?
- 2018 British_Isles_heat_wave
- 2018 Sweden wildfires