2018 British Isles cold wave

The Hartmut cold spell was caused by a large arctic airmass with anticyclonic structure, stretching from the Russian Far East to the British Isles covering large parts of Asia and almost all of Europe. The anticyclone, centred on Scandinavia,^[9] was the dominant high pressure area in the weather system and represented its European part. North Asia was covered by other anticyclones that belong to that giant arctic airmass. The anticyclone brought cold easterly winds into Europe and the British Isles leading to snowfall and sub-zero temperatures as a result of freezing air from Siberia.^[10][11] Ireland was predicted to experience its worst winter for at least 30 years.^[12][13] In the United Kingdom the Met Office issued a red snow warning, meaning a potential risk to life.^[14]

The anticyclone was such an intense high pressure system that it evolved into an anticyclonic storm, and was named Hartmut. A gust of 187 km/h (116 mph) was registered in the Øvre Dividal National Park in Norway, relatively near to the anticyclonic centre.^[15] Other hurricane-force gusts delivered by Hartmut were registered across Europe, particularly over Scandinavia and the British Isles. Such hurricane-force anticyclonic storms are not extremely rare, but occur less often than cyclonic storms of similar intensity.

Sixteen weather-related deaths include that of a seven-year-old girl on Thursday 1 March in Looe, Cornwall, when she was hit by a car that slid on ice into a bungalow. On Wednesday 28 February, Stephen Cavanagh, 60, died after trying to save his dog from a lake in Welling, South East London. Also on Wednesday, a 46-year-old man died in a crash and a 75-year-old woman was found dead underneath her car in Farsley. A carer from Glasgow died on her way to work and a 52-year-old homeless man was found dead freezing inside his tent. On Tuesday 27 February, four people died in two separate weather-related crashes. A 20-year-old also died after slipping and falling whilst crossing a bridge in Haddington, East Lothian. This followed the death of a man trying to help another driver in the snowy conditions in Bergh Apton, Norfolk, who suffered a heart attack. A 70-year-old also died after being rescued from icy cliffs in Torquay.

Storm Emma brought chaos with heavy snow and strong winds to the South of Ireland, South West England and Southern Wales on 2–3 March 2018 with up to 50 cm (20 in) of snow in some elevated areas.^[30] High winds brought disruption to other parts of Great Britain and Ireland. It also brought rail disruption as several trains became stranded, full of passengers, for up to 14 hours.^[31] Daytime temperatures were also very suppressed, some places not getting above −12 °C (10 °F).^[3]

Following a brief spell of warmer weather, a fresh cold snap nicknamed the "Mini Beast from the East" was forecast to bring another covering of snow on the weekend of 17 and 18 March. However, due to the onset of spring, and a higher sun position, it was forecast that the effect would be less severe than on the previous occasion, for the ground was warmer than before, and thus the snow would melt more quickly.^[32][33]

Snow showers began to affect parts of Britain and Ireland on 17 March, with north-east England, the North Midlands, and parts of southern England experiencing the heaviest snowfall. The snow was accompanied by strong winds, forecast to be as high as 110 km/h (70 mph), and the Met Office issued an amber weather warning effective from the afternoon of 17 March.^[34] Snow showers continued to affect parts of the UK and Ireland on 18 March, with south-west England the most severely affected. The adverse weather conditions forced the cancellation of some sporting events, including the Reading Half Marathon, while Ireland's rugby union team, who had won the 2018 Six Nations Championship, cancelled their homecoming "due to heavy snowfall" with no new date confirmed.^[35]

• 2018–19 European winter
• 2013–14 United Kingdom winter floods