The UK is experiencing a heatwave – unofficially

The UK does not have an official definition of a heatwave, although the Met Office is working on one. However, the Geneva-based World Meteorological Organisation defines it as a period during which the daily maximum temperature exceeds the maximum normal temperature by 5C for more than five consecutive days. Weather experts were happy to use the term last week after temperatures nudged the low 30s from Monday to Friday.

Records have been broken – sort of

Met Office forecasters report that last month could be among the five warmest, driest and sunniest Junes since records began in 1910. Last week, for the first time in five years, all four of the UK’s nations saw temperatures hit 30C. Cue headlines about parts of Britain being hotter than Athens/Istanbul/Rome. The mercury soared to 33C in Porthmadog, Wales, a record for 2018. However, temperatures are now predicted to slip a little, to the high 20s. We’re unlikely to beat the hottest temperature seen in the UK, 38.5C at Faversham, Kent on 10 August 2003. And we’re a long way from June 1976, when temperatures topped 32C every day in parts of the country for 15 consecutive days.

It’s all about the jet stream

The jet stream, a core of strong winds blowing from west to east between five and seven miles above the Earth, has moved to the north of Britain, dragging with it a belt of high pressure that now blankets the country. This is blocking out cloud and rain and sucking in warm air from southern Europe. Combine this with long June days, when the sun is at its highest in the sky, and it is no surprise that temperatures have rocketed.

Getting around is tricky (and sticky)

Gritters are out in parts of the country as roads melt in the heat, while train tracks are buckling as they reach temperatures of 50C, causing lengthy delays. Passengers on the London underground have been enduring temperatures as high as 35.4C, which is five degrees hotter than the legal maximum for transporting cattle.

It’s bad news for some flora and fauna ...

There have been several devastating blazes on moorland, including Saddleworth Moor near Manchester, which firefighters say could take weeks to extinguish. The RSPB is warning that high temperatures pose a threat to many of our favourite garden birds, such as robins, blue tits and blackbirds, while the RSPCA has called on pet owners to keep a close eye on their animals after receiving 625 calls in two weeks about animals in hot environments – the majority of them dogs in cars. Farmers are becoming increasingly worried about the impact on crops and cattle. The Environment Agency has asked the public to watch for fish “gasping” in the hot weather, which lowers oxygen levels in the water. Last Thursday it had to carry out a “fish rescue” on the River Teme on the Shropshire and Herefordshire border, transferring 130 salmon and trout from the river before it dried up completely.

... but not all

There has been a big increase in the number of bloodsucking horseflies, which are now at levels commonly found in Mediterranean countries. There are also reports of a surfeit of pollen beetles and flying ants in some parts of the country. Butterfly and bee numbers are expected to rise as a result of the hot weather, too.

Hosepipe bans are back

Severn Trent, one of the biggest utilities, is warning people to conserve supplies. Homes that it supplies in Shropshire, Staffordshire and Derbyshire have been temporarily without water as demand has outstripped supply across its network. United Utilities, South Staffs Water and Anglian Water are among other firms urging customers to do the same. NI Water is asking people not to use water for washing cars, filling pools or sprinkling gardens, as supply failures have already hit some areas.

Some businesses are booming

Research firm Nielsen said that last month Britain’s major retailers enjoyed the largest annual revenue rise for four years, up 4% compared with June the previous year. Sales of hand-held ice-creams increased by 24% on the previous June. More people also dined alfresco, with demand for quiche up 11% and worries about a lettuce shortage. Camp sites are also doing well. However, a shortage of CO2 has see some pubs and retailers having to restrict sales of certain beers as demand for them soars with the World Cup and the hot weather.

It could mean rain in Spain

High pressure in the higher latitudes often means lower temperatures and heavier rainfall in the Iberia peninsula, according to meteorologists. Britons who usually holiday in the wetter parts of Spain or Portugal at this time of year might do just as well, weather-wise, by staying at home.

Don’t put the shades away just yet

Grahame Madge, press officer at the Met Office, says a slight cooling influence is coming in from across the North Sea, but its effect will be limited as in the next few days the humidity will rise. “In terms of the medium range, we’re expecting this pattern to remain in place until the middle of next week, with the limited prospect of thunderstorms in the south-west of England on Sunday. The Weather Company, which correctly predicted June’s hot spell, suggests the good weather will last for another couple of weeks at least – and possibly much longer. Dr Todd Crawford, its chief meteorologist, said: “If we look ahead through July, there are a lot of days with temperatures around 27C to 28C coming up. What we have seen in June so far should hang on for at least the first half of July.”