Extreme weather events are rare, but research shows that with climate change they are likely to become more frequent

As experience has shown, severe weather can take a variety of forms and at times can cause significant problems and disruption to normal life. Over the coming years we are likely to see rising temperatures and sea levels and an increase in the frequency and severity of extreme weather events in the United Kingdom.

Storms and Gales
The most significant storms in recent decades were those of 16 October 1987 and 25 January 1990. The first brought down an estimated 15 million trees in the south-east of England. As the peak wind speeds occurred overnight, there were fewer deaths and injuries than there might have been, given that the storm crossed such a densely populated area.

By contrast, the 1990 storm which occurred during the daytime was more extensive and had higher peak wind speeds. The more northerly track meant that the storm crossed areas that were on the whole less wooded than those affected by the 1987 storm. The net effect was a much higher death toll but less damage to trees and property.

More recently, on 18 January 2007, a storm battered many parts of the UK, with gusts of wind up to 77mph recorded at Heathrow. This caused nine deaths and widespread damage to trees and buildings across the UK, along with power disruption.

Low Temperatures and Heavy Snow
There have been a number of recorded occasions of snow covering large areas of the country for over a week.

The winter of 2009–10 saw a prolonged spell of cold weather that lasted for approximately a month between mid- December and mid-January. During this time snow fell widely and sometimes heavily across the UK, with notable falls of up to 40cm recorded in parts of northwest England and south and east Scotland. Many other areas experienced snow cover of 10cm or more throughout this period.

In Northern Ireland in February 2001 strong north-easterly winds and heavy snow caused travel disruption for up to five days and brought down power lines (resulting in power cuts to 70,000 homes), mostly in Counties Antrim and Down.

Earlier, more severe events include periods of snow in 1947 and also in 1962– 63, which was the coldest winter in over 250 years. As the climate continues to change, the frequency of more extreme weather events is likely to increase, though winters are expected to become milder and wetter on average. Extreme snowfall events may become less frequent in the south of the UK in the future.

Temperatures of 32°C or more (the threshold used by the Met Office to define a heatwave) were widespread during August 1990, having been recorded in virtually all parts of England and some parts of Wales. The years 1976 and 1911 were the only other occasions on which half or more of England experienced 32°C. In terms of persistence, 1976 ranks the highest with 32°C being exceeded at one or more places in the UK on 15 consecutive days from 23 June to 7 July.

The hot summer of 2003 is estimated to have resulted in 2,045 excess deaths (that is, deaths that occur above what is expected for that time of year), mainly among vulnerable populations.

In July 2019, the Met Office observations team received a new provisional figure of 38.7 Celsius from Cambridge University Botanic Garden.  The current highest temperature on record for the United Kingdom is 38.5 Celsius, recorded in Faversham in August 2003.

Droughts are regular events and vary in intensity and duration across the country. A drought does not arrive without warning. Routine monitoring of drought indicators such as river or groundwater sites by the Environment Agency in England, Natural Resources Wales, the Northern Ireland Environment Agency and the Scottish Environment Protection Agency picks up indications of any significant deficits developing.

Periodic restrictions on non-essential water use are an integral part of water resource planning by water companies. During the 2010–12 drought, despite some of parts of south-east and eastern England recording their lowest 18-month rainfall (for the period ending March 2012) in at least 100 years.

Climate change may produce more droughts but not necessarily a more frequent use of restrictions. Water resource and drought planning must be dynamic to meet the challenges.