The 2017–2018 European windstorm season was the third instance of seasonal European windstorm naming. France, Spain and Portugal took part in winter storm naming for the first time this season.

The season started on 12 September 2017 with the formation of Storm Aileen. It was subsequently marked by many high-impact storms which caused severe loss of life and widespread damage, including Ophelia, Eleanor, David and Emma. The season concluded on 17 June 2018 with the dissipation of off-season Storm Hector.

Background and naming

In 2015, the Met Office and Met Éireann announced a pilot project to name storm warnings as part of the Name our Storms project for wind storms and asked the public for suggestions. The meteorological offices produced a full list of names for 2015–16 and 2016–17, common to both the UK and Ireland. A new list of names was released on 6 September 2017 for the 2017–18 season. Names in the UK will be based on the National Severe Weather Warning Service, when a storm is assessed to have the potential for an Amber 'be prepared' or Red 'take action (danger to life)' warning.

A storm will be named when it is deemed able to have a "substantial" impact on the UK or Ireland. They will be taken from the list, in alphabetical order, alternating between male and female names—the same naming convention that is used by the United States for tropical cyclones. In the case of storms resulting from ex-tropical storms and hurricanes, the original name allocated by the US National Hurricane Center will be used, an example of which during this season being Ophelia. Met Éireann name any storm which triggers a status Orange or Red weather warning for wind. The basis for such, as outlined on their weather warning service, are mean wind speeds in excess of or gusts over . Similarly, the Met Office name storms that have the potential to cause medium (Amber) or high (Red) impacts to the UK. It describes the wind strength relative to observations such as "falling trees or tiles, other items like garden furniture being blown around and even a number of properties left without electrical power."

On 1 December 2017, the national meteorological services of Spain (Aemet), France (Météo-France) and Portugal (IPMA) announced that they would begin naming storms affecting their nations in co-ordination, under the auspices of EUMETNET.

United Kingdom and Ireland Aileen Brian Caroline Dylan Eleanor Fionn Georgina Hector

The Met Office's and Met Éireann's announcements of the season's names also noted that Fionn is to be pronounced Fyunn, Niall is to be pronounced Nye-ul and Tali is to be pronounced Tarly.

France, Spain and Portugal Ana Bruno Carmen David Emma Felix Gisele Hugo Irene

Other naming systems One former Atlantic hurricane transitioned into a European windstorm and retained its name as assigned by the National Hurricane Center in Miami, Florida:

Ophelia

Another internationally recognised, but unofficial, naming system for European windstorms is the Adopt a Vortex program of the Free University of Berlin. Participants can ask the FUB to give their names, for example as a birthday present, to high or low pressure systems that affect European weather. The naming service of the FUB is commercial and is the main meteorological naming system in Germany. The names Xavier and Herwart were given by the FUB to major storms this season. Its naming program is recognised in some other European countries, although the British-Irish and the French-Spanish-Portuguese naming co-operations are gaining importance. Furthermore, besides of the three internationally recognised naming systems (the two European co-operations and the FUB system), many European countries (Norway, Finland, Denmark etc.) give their own names to cyclones. One of the 16 storms of the season was not named by the three main naming systems: instead it was called Cora in Norway and Aku in Finland.

Season summary

The 2017–18 UK and Ireland windstorm season began on September with storm Aileen, which brought strong winds to Scotland and Northern England on 13 September. Then followed Ophelia which was once a Category 3 major hurricane and the easternmost major hurricane on record; a red (severe) wind warning was issued for many parts in Ireland. Less than a week later, storm Brian rapidly intensified from a trough of low pressure out in the Atlantic. After a rather quiet November without any named systems (like quiet Septembers and Octobers of the previous two years), Caroline and Dylan formed in December followed by Eleanor early in January 2018. In the middle of January, the extremely deep and large arctic low Fionn affected both the UK and Ireland and steered David, a smaller but more intense storm, on a westerly track over Ireland, the UK and Central Europe. The last storm in January was Georgina, a cyclone that mainly affected Ireland and Scotland.

A total of 10 storms affected both the UK and Ireland in that season. Three of these—Ophelia, David and Emma—were named by foreign agencies. Six storms were named by the new co-operation of the meteorological services of France, Spain and Portugal. Two of these—David and Emma—also affected Britain and Ireland significantly.

The impact of the deadly winter storm Emma was intensified by the collision with the Beast from the East cold wave (anticyclone Hartmut). Cora, another significant windstorm, affected Scandinavia, Norway and Sweden in particular. Cora delivered the highest known gust of the European windstorm season. As a European total, 18 windstorms (one "off-season") affected the continent.

Storms Storm Aileen

Aileen formed on 12 September, with the Met Office issuing an Amber wind warning, becoming the first named storm of the season. Aileen affected Cheshire, Lancashire, Derbyshire, Yorkshire, Nottinghamshire and Lincolnshire during the evening of 12 September and into the morning of 13 September with winds of over . Gusts up to around were also seen in exposed locations such as along coastlines and over high ground in these areas. A Yellow weather warning for rain was also issued for parts of Northern Ireland, northern England and southern Scotland, as Aileen dropped of rain within 6–9 hours in these areas, causing some disruption from localised flooding. The heaviest rainfall was recorded at Bainbridge, North Yorkshire, with falling overnight.

During Aileen, approximately 60,000 homes in Wales and almost 9,000 across England suffered power cuts. The strongest gusts, of , were recorded at The Needles, Isle of Wight. The strongest gust on mainland Britain, of , was recorded at Mumbles, Wales.

Aileen later crossed the North Sea and intensified, going on to affect Germany, where it was known as Cyclone Sebastian.

Ex-Hurricane Ophelia

On 12 October, the Met Office issued yellow weather warnings relating to the extra-tropical remnants of the former Hurricane Ophelia, estimated to affect the UK and Ireland on 16 October. Met Éireann issued an update on 12 October in response to media coverage about possible impacts which might occur in Ireland, highlighting the uncertainties still in the forecast modelling. Met Éireann asked people to keep up to date with changes in the forecast as the storm evolved and confidence in any likely impacts increased. On 14 October Met Éireann issued a red warning for the counties of Galway, Mayo, Clare, Cork and Kerry for 16–17 October, (extended to Limerick, Waterford and Wexford on 15 October) with an orange warning for the rest of the country. Red warnings were extended again on the evening of 15 October to the whole of Ireland. On 15 October the Met Office issued amber warnings for the six counties of Northern Ireland, and updated the yellow warnings in place for England, Wales and Scotland. The Met Office updated its amber warnings to include parts of west Wales, southwest Scotland and the Isle of Man on the morning of 16 October.

In County Waterford, a woman was killed when a tree fell on her car, caused by the winds from Ophelia's remnants. A man died near Dundalk, County Louth, after a tree struck his car. A man was killed in Cahir, County Tipperary, while trying to clear a fallen tree with a chainsaw. Two more people were subsequently killed in Ireland from the combined effects of Ophelia and the subsequent Storm Brian.

Storm Brian

On 13 October, the US National Hurricane Center designated a tropical wave in the Atlantic Ocean to the east of the Lesser Antilles as Invest 92L, giving the system a 40% chance of developing into a tropical cyclone. The NHC continued monitoring the system as it moved slowly north-west, bringing heavy rainfall and flooding to Puerto Rico and the British and US Virgin Islands before turning to the north-east. However, on 16 October, the NHC discontinued monitoring the system as it passed Bermuda without any considerable impact, having failed to transition into a tropical cyclone.

Subsequently, the area of low pressure began to rapidly intensify as it accelerated eastward across the open Atlantic, developing into a powerful extratropical cyclone. On 19 October, Met Éireann issued an orange wind warning for 21 October in counties Galway and Mayo, thus naming storm Brian. On 20 October Met Éireann extended orange warnings to the counties of Clare, Kerry, Waterford and Wexford. The UK Environment Agency warned that storm Brian could combine with high tides and lead to a heightened risk of flooding on the south coast of the UK.

Brian moved over Ireland close to Galway around 07:00 local time on 21 October.

A 67-year-old man drowned after being swept from the sea wall at Dawlish during the storm. Two more people were killed in Ireland from the combined effects of Brian and the prior Ex-Hurricane Ophelia.

Storm Caroline

The Met Office named storm Caroline on 5 December to affect Scotland on 7 December, with a yellow warning for wind, which was upgraded on 6 December to an amber warning for the Western Isles, Northern Isles and northern Scotland. Met Éireann issued a yellow warning for wind to the counties of Donegal, Galway, Leitrim, Mayo, Sligo, Clare and Kerry.

Storm Ana

Storm Ana was the first storm to ever be officially named by Météo-France, Aemet and IPMA. It formed on 10 December as an area of low pressure that underwent explosive cyclogenesis to the northwest of Iberia passing through the Bay of Biscay into France on the morning of 11 December. It then took a northeasterly direction to affect the Low Countries, Germany, Austria, Scandinavia and eventually Russia.

The highest gusts from Ana reached in the Austrian Alps, and its minimal pressure reached on the morning of 11 December. Severe flooding was reported in the Emilia-Romagna region of northern Italy on 12 December, caused by heavy rainfall from a trailing front from Ana and rapid snowmelt due to a large temperature rise caused by Ana's passage. Damage from flooding in Italy reached €105 million.

Storm Bruno

On 26 December 2017, wind warnings were issued in Spain for an area of low pressure that was expected to undergo explosive cyclogenesis. Ultimately, Storm Bruno brought over of snow, wind gusts exceeding , and waves as high as to Spain. One fatality occurred after a man drowned while windsurfing in rough seas. Another fatality occurred after a man was swept off his balcony by high winds and onto his patio, where he immediately succumbed to his injuries.

Storm Dylan