Why is the UK Having a Heatwave?

According to the World Meteorological Organisation a heatwave is a “marked unusual hot weather over a region persisting at least two consecutive days”.

Usually, such a definition would not be something we may be interested in knowing, but perhaps times are changing in this country. For the UK, this summer is shaping up to be one of the hottest of all time. Forecasters at the Met Office have been reading out temperatures of 34C over the last few days (24-27th July), and even with the onset of storms in some regions, it looks like it will be remaining warm for a while yet.

The Met Office reports that “the temperatures so far this summer have been remarkable… between 1 June to 16 July, the average daily maximum temperature across the country was 20.9 °C.” This average has increased over the past two weeks, with many parts of Britain experiencing heat in excess of 28C. Porthmadog, in Wales, now holds the record for the hottest day of June, when it reached 33C on the 28th. This was beaten in Suffolk, though, when on 22nd July temperatures soared to 33.3C.

The UK’s heatwave has been caused by a jet stream looping to the north of the UK, creating an area of ‘home grown’ high pressure. Met Office forecaster Mark Foster explains, “Long days, very still conditions and clear skies helped June temperatures to get very intense… The sun in June is relatively the highest it gets in the sky and heat can build up over successive days.”

The build of heat Foster refers to leads to extreme levels of pollen and UV, meaning hay fever sufferers have been having a particularly bad year. As the sunshine continues to blaze in our skies, experts have warned The Telegraph “…  the heatwave risks bringing on a faux autumn with prematurely ripening fruits and browning leaves.” If hedgerow fruits mature two months ahead of their usual growth pattern in some parts of the country, that will cause disaster in the autumn for the animals that rely on them for food.

There is no way of accurately predicting how much longer this sunshine will last. The Met Office explains high pressure systems are “slow moving and can persist over an area for a prolonged period of time such as days or weeks”. The longer this weather lasts, the higher the risk of thunderstorms and flash floods resulting from heavy rain fall hitting dry ground. Rain-soaked days are traditionally associated with a British summer, but between 1st June and 16th July the UK received just 47 mm of rain. This makes it the driest start to summer since 1961. The summer of 1976, which is currently the hottest summer on record, had an average temperature of 21.0 °C. In 1976 there were 69 days of sunshine in total. The Met Office has confirmed that if the “rest of the summer is average, 2018 will certainly rank in the top 10 warmest summers on record and if we continue to see above average temperatures, it could well be record breaking.”

While humans are suffering from heat-related exhaustion, the threat of water restrictions and coping with searingly hot commutes to work, there are many other, more far reaching implications to the heatwave. Farmers are struggling to keep their livestock fit and healthy. Speaking to Sky News, Gloucestershire farmer Luke Wilson said after his “250 sheep were sheared in June [and] they have been relatively happy, but a lack of grass is the biggest problem… It’s their food which is a concern, I only feed my sheep on grass and we’re about to run out due to a lack of rain.”

Crop growers are also worried. Hot temperatures mean more people are eating salad foods like lettuce. However, many types of lettuce won’t grow if it’s too hot, and there are fears that supplies will run low soon. Broccoli also refuses to grow if too hot, and so prices will rise as supply diminishes. Insects such as dragonflies are in danger as their water supplies dry up. Bees, however, are enjoying the dry conditions, and are experiencing a much needed boost; which has lead to a bumper year of flowers.

One occupation, however, is enjoying a bumper year of discovery thanks to the effects of the scorching temperatures. Archaeologists across the UK are making a great many discoveries, just as they did in 1976. Dry ground highlights the hidden features of the earth, especially when observed from above. For example, the drought in Ireland has lead to failing crops, and so has exposed as long forgotten henge at Brú na Bóinne. The Express explains that, “The circular design was spotted by photographer and author Anthony Murphy who was flying his drone nearby above the site when he stumbled upon it. The pattern is 150 metres (492 ft) in diameter, but experts are unsure what its purpose is.”

The all-time July heat record is 36.7C , set at Heathrow airport on 1st July 2015. Whether or not that record breaks this year isn’t entirely clear now, but if the temperature trends of recent times continue to rise as they have been, it may be that sometime in the next few years it will be.

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Dr Kathryn Bates is a graduate of archaeology and history. She has excavated across the world as an archaeologist, and tutored medieval history at Leicester University. She joined the administrative team at Oxford Open Learning twelve years ago. Alongside her distance learning work, Dr Bates is a bestselling novelist, and an itinerant creative writing tutor for primary school children.

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