Wales Climate – Sep 2026September 2026 Update

The Bristol Channel flood of 1607

Britain's deadliest recorded flood drowns both shores of the Bristol Channel on 30 January 1607, killing an estimated 500-2,000 people and inundating about 200 square miles of farmland up to 14 miles inland - the Somerset Levels in England and the Gwent Levels in south Wales alike.

Wikipedia, Phys.org

Post-WWII industrial expansion begins

After the Second World War, coal and oil use grew rapidly across Europe, North America and the Soviet Union. Global sulphur dioxide emissions rose from about 30 to about 130 million tonnes a year by 1980, and the sulphate haze they formed masked part of the greenhouse warming underneath - the effect known as 'global dimming'.

Klimont et al. 2013

UK Clean Air Act

Wales was covered by the Clean Air Act 1956 alongside England and Scotland, gaining smoke control areas and curbs on domestic coal burning from the same date - unlike Northern Ireland, which the Act did not extend to and which legislated separately in 1964.

The National Archives, Clean Air Act 1956, The Clean Air Act 1964 (Appointed Day)…

The Big Freeze of 1962-63

A blizzard on 29-30 December 1962 struck Wales and south-west England, piling snowdrifts up to 6 metres deep at the start of a winter that went on to be the coldest since at least 1895 in every UK meteorological district.

Wikipedia, Wikipedia (2), Royal Meteorological Society, Norfolk Live

Agung eruption

Agung's eruption in Bali put a veil of sulphate haze into the stratosphere that cooled global temperature by about 0.3°C over 1963-66.

Smithsonian Global Volcanism Program, NOAA Global Monitoring Laboratory

The 1976 UK drought

In south east Wales, the Brecon reservoirs dried up completely and mains water was switched off for up to 17 hours a day during the drought.

Countryfile

Global SO2 emissions peak

Global sulphur dioxide emissions peak at about 130 million tonnes a year, then begin a long decline as Europe, North America and Japan clean up their air. As the aerosol mask thins, the rate of global warming picks up through the 1980s.

Klimont et al. 2013

The late April snowstorm of 1981

An exceptionally late snowstorm crossed Britain between 23 and 26 April 1981. More than 30cm fell widely across Wales, southern England, the Midlands and the north west, 20cm of it on the 25th alone across western England and Wales - deep snow in a month when spring is normally well under way.

Wikipedia

The 1981 tornado outbreak

The largest tornado outbreak ever recorded in Europe began in Wales. On the morning of 23 November 1981 the first tornado touched down at Rhosgoch on Anglesey and tracked towards Amlwch, and minutes later the strongest of the day, rated F2, damaged 20 houses in Holyhead. Over the next five and a half hours 104 tornadoes touched down across Wales and England.

Wikipedia, Wikipedia (2)

El Chichón eruption

A sulphur-rich eruption in Mexico whose aerosol cloud stayed in the stratosphere for more than two years, cooling the Northern Hemisphere by about 0.2°C.

Smithsonian Global Volcanism Program

Daytime warming catches up with the night-led pattern

Across 1961-90, 81% of the world's land saw nights warming faster than days. Across 1991-2020 the pattern reversed: 70% saw days warming faster, as the industrial haze that had been dimming daytime sunshine was cleaned up. The study compares two fixed thirty-year windows; measured as a turning point, this site's own global series turns around 1982.

Zhong et al. 2023

The Burns' Day Storm

Aberporth in west Wales recorded the storm's joint-highest gust, 107mph, on 25 January 1990. Gusts topped 92mph all along the west Welsh coast in a storm that killed 47 people across the UK and felled around 3 million trees.

Met Office, Royal Meteorological Society

August 1990 UK heatwave breaks 79-year record

The August 1990 heatwave reaches 35.2°C at Hawarden Bridge, Flintshire (2 August) - Wales's own temperature record at the time, which stood until 2022.

Deeside.com

Positive NAO phase dominates the 1990s

Wales sits on the wet side of a positive NAO. The strengthened south-westerlies of the 1990s met the Welsh uplands head-on, and that orographic lift is what converts a shift in the Atlantic jet into measurably wetter, milder, stormier winters here.

Hurrell 1995, Science, Atmosphere, 2021, Frontiers, 2022NAO Tracker

The Towyn coastal flood

Gale-force winds meet a high spring tide on 26 February 1990 and breach the sea wall at Towyn on the north Wales coast. Ten square kilometres flood, 2,800 properties are affected and around 6,000 people are evacuated - one of the largest peacetime evacuations in Wales.

North Wales Live, SurgeWatch

Atlantic Multidecadal Oscillation flips to a warm phase

The Atlantic Multidecadal Oscillation flipped to a warm phase in 1995. For the UK it is one of the background rhythms sitting underneath the warming trend: warm AMO phases are associated with warmer North Atlantic surface waters on the UK's doorstep, and have been linked to wetter summers in parts of north-west Europe. It is a natural cycle of roughly 60-70 years, so it shifts the baseline rather than driving the long-term trend - which matters when reading any UK record set since the mid-1990s.

Learn more →

The autumn 2000 floods

2000 is Wales's wettest year in this site's record, which begins in 1900, at 1,886mm, and September-November brought 739mm - its wettest autumn too. Across England and Wales it was the wettest autumn since records began in 1766 and the most extensive flooding since 1947, with around 10,000 homes and businesses flooded at 700 locations.

Met Office, Parliament POST

August 2003 European heatwave (UK)

The August 2003 heatwave reaches 33.0°C at Valley, Anglesey (5 August) - beating Wales's previous record of 32.8°C, set in 1948.

North Wales Live

Summer 2007 UK floods

Wales shares in the England and Wales record of 414.1mm from May to July 2007, the wettest such spell since the series began in 1766, and South Wales is among the areas flooded in the final episode on 28 July.

Wikipedia / GOV.UK flood cost report, Met Office

Negative NAO blocking cluster, 2009-2013

Llysdinam in Powys fell to -17.5°C in December 2010, Wales' low point in a month that was the UK's coldest December since Met Office records began, driven by a blocked negative-NAO pattern with high pressure parked over Greenland.

4byo, Met Office, WikipediaNAO Tracker

Start of the sustained rise in UK heatwave frequency

Wales's own Heatwave Days count rose from a decade mean of 3.48 days in the 2000s to 9.18 in the 2010s, and 14.55 so far in the 2020s - one of the strongest versions of this UK-wide acceleration in the site's own regional data.

Met Office, State of the UK Climate

UK's post-2013 warmth acceleration

7 of Wales's own 10 warmest years on record have occurred since 2013, matching the UK-wide pattern.

Met Office, State of the UK Climate

England and Wales' wettest winter since 1766

Winter 2013-14 (December to February) brought Wales 724mm of rain, 175% of the 1961-90 average - its 2nd-wettest winter since this site's Met Office regional record begins in 1901, a whisker behind 2015-16. Across England and Wales as a whole it was the wettest winter since the series began in 1766.

Met Office, Kendon et al. 2015, England and Wales Precipitation series

2015-2025: the eleven warmest years on record

Globally, the eleven warmest years on record have all happened since 2015. Wales's own record is a looser fit - six of its eleven warmest fall in that span, with 2014, 2011, 2007, 2006 and 1949 outside it. Its warmest year is 2023.

Learn more →

The Beast from the East

The 'Beast from the East', compounded by Storm Emma, brings up to 50cm of snow to parts of South Wales (2-3 March). It followed a sudden stratospheric warming in mid-February that split the polar vortex.

Wikipedia, Wikipedia (2)Polar Vortex Tracker

Low-sulphur shipping fuel rule (IMO 2020)

New international shipping rules cut the sulphur allowed in ship fuel from 3.5% to 0.5% almost overnight, removing about 8 million tonnes of sulphur dioxide a year. With less sulphate haze over the oceans, it may have added around 0.1°C of warming by 2023-24.

Gettelman et al. 2024

February 2020 floods (Storms Ciara & Dennis)

Wales has its wettest February since records began in 1862, and Storms Ciara and Dennis bring the worst flooding since December 1979 - often to the same communities. The Taff at Pontypridd reaches its highest level since records began in 1968 and the Usk breaks its 1994 record; over 3,000 properties flood, at a cost above £81 million.

Natural Resources Wales

The UK's wettest February on record, 2020

February 2020 was Wales's wettest February in this site's Met Office record from 1900 - 295.3mm, nearly three times its 1961-90 average - as Storms Ciara, Dennis and Jorge followed one another in on a strong, southward-shifted jet stream. It beat the 267.7mm of February 2002, and Storm Dennis brought severe flooding to south Wales.

Davies et al. (2021), Carbon Brief / Met Office, NOAA CPCPolar Vortex / AO

Storm Christoph floods, January 2021

Storm Christoph's heaviest rain fell across north Wales and northern England on 19-21 January 2021. The Dee at Bangor-on-Dee, near Wrexham, rose to its highest level on record, and around 2,000 families across Wrexham, Merseyside and Manchester were moved from their homes.

Met Office, FloodList

The UK's first 40°C day

Wales set a new national temperature record of 37.1°C at Hawarden Airport, Flintshire, on 18 July 2022 - beating the 35.2°C that had stood at Hawarden Bridge since the August 1990 heatwave. The UK passed 40°C for the first time the following day.

Met Office review (via Carbon Brief), Met Office, Wikipedia, Met Office (2)