2013 Great Britain and Ireland heat wave

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The 2013 heat wave in the United Kingdom and Ireland was a period of unusually hot weather primarily in July 2013, with isolated warm days in June and August. A prolonged high pressure system over Britain and Ireland caused higher than average temperatures for 19 consecutive days in July, reaching 33.5 °C (92.3 °F) at Heathrow and Northolt.[1] Following a brief period of cooler weather at the end of July, temperatures temporarily rose again, peaking at 34.1 °C (93.4 °F) on 1 August in the United Kingdom, the warmest the country had seen since July 2006,[2] and 31 °C (88 °F) in Ireland.[3] At 19 days, the July heatwave was the longest continuous period of hot weather in the UK since August 1997.[1]


On 4 July the Met Office predicted a long spell of warm weather over England and Wales to last until the middle of the month, with the south-east set to experience close to 30 °C (86 °F), and Scotland and Northern Ireland expected to avoid the warmest weather.[4] In the following week temperatures reached 29.7 °C (85.5 °F) on the south coast[5] and climbed to 30 °C (86 °F) in Northern Ireland, the highest temperature seen there since 2006.[6]

Heat waves in the United Kingdom are declared when the threshold maximum day temperature and a minimum night temperature are exceeded for at least two consecutive days. The threshold temperatures differ region by region, but the average is 30 °C (86 °F) for the day and 15 °C (59 °F) for the night.[7] On 12 July, the Met Office released heat wave alerts across much of England, with Yorkshire and the Humber placed in the level three category out of four alert levels.[8]

On 17 July, the Met Office upgraded London and South East England to level three following the fifth consecutive day of temperatures over 30 °C (86 °F).[9]

The heatwave ended on 23 July with heavy thunderstorms, bringing flooding and lightning strikes that caused delays on motorways and railways, power cuts and fires.[10] Despite this, temperatures still remained above average for the time of year. On 29 July, another spell of thunderstorms hit the UK. Manchester for example was hit by three thunderstorms in eight hours. Three days later on 1 August, the temperatures rose again, recording the warmest August temperature since 2003.[11] In some places, 1 August was actually warmer than all of the days in July. London Heathrow recorded 34.1 °C (93.4 °F), which exceeded the previous record of 33.5 °C (92.3 °F) which was recorded on 22 July. By 2 August however, temperatures began to return to normal.


On 18 July, the London School of Hygiene and Tropical Medicine reported that the first 9 days of the heat wave had caused up to an additional 760 deaths in the UK.[12]

Emergency services[edit]

The heat wave led to rises in both the number of calls to the emergency services and admissions to A&E departments.[13][14] The large numbers of people using rivers, lakes and the sea to cool off led to a large increase in the number of calls to lifeguards.[15] The London Fire Brigade reported having to deal with double the number of grass fires in the capital compared to the previous year.[16] Wildfires were also reported in Epping Forest in Essex, the Dorset coast, the valleys of southern Wales and Tentsmuir Forest in Scotland.[14][17]


Following declines in the summer of 2012 due to wet and windy conditions, butterfly numbers saw a surge due to the prolonged warm weather.[18] The warmer waters around the British coasts also led to an increase in the number of jellyfish sightings, particularly the moon jellyfish.[19]

The death of thousands of fish in rivers and lakes was attributed to the elevated temperatures lowering the amount of oxygen in the water to toxic levels.[20]


  1. ^ a b "July finishes in top three sunniest and warmest". Met Office. 5 August 2013. Retrieved 29 October 2013.
  2. ^ "Warmest, driest and sunniest summer since 2006". Met Office. 30 August 2013. Retrieved 29 October 2013.
  3. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2016-10-02. Retrieved 2013-09-02.CS1 maint: archived copy as title (link)
  4. ^ Siddique, Haroon (4 July 2013). "Heatwave to last until mid-July in England and Wales, say forecasters". The Guardian. London: Guardian Media Group. Retrieved 29 October 2013.
  5. ^ Carter, Claire (9 July 2013). "Heatwave expected to continue until the weekend". The Telegraph. London: Telegraph Media Group. Retrieved 29 October 2013.
  6. ^ Stewart, Linda (9 July 2013). "Temperature soars to 30C in Northern Ireland as heatwave is set to continue". Belfast Telegraph. Independent News & Media. Retrieved 29 October 2013.
  7. ^ "Heatwave". Met Office. Retrieved 29 October 2013.
  8. ^ "England heatwave alerts issued". BBC News. BBC. 12 July 2013. Retrieved 29 October 2013.
  9. ^ Jones, Sam (17 July 2013). "Met Office issues heatwave alert as temperatures pass 30C for fifth day". The Guardian. London: Guardian Media Group. Retrieved 29 October 2013.
  10. ^ Morris, Steven (23 July 2013). "Thunderstorms and lightning break British heatwave". The Guardian. London: Guardian Media Group. Retrieved 29 October 2013.
  11. ^ Williams, Rob (1 August 2013). "Britain sees hottest August temperatures for ten years as heatwave returns - but just for a day..." The Independent. London: Independent Print Limited. Retrieved 29 October 2013.
  12. ^ Silverman, Rosa (18 July 2013). "Heatwave deaths: 760 lives claimed by hot weather as high temperatures continue". The Telegraph. London: Telegraph Media Group. Retrieved 29 October 2013.
  13. ^ Collins, Nick (7 July 2013). "Heatwave prompts surge in ambulance calls". The Telegraph. London: Telegraph Media Group.
  14. ^ a b Bawden, Tom; Cooper, Charlie (19 July 2013). "Heatwave latest: Spike in A&E admissions, wildfires and melting roads as Britain battles seventh day of 30-plus temperatures". The Independent. London: Independent Print Limited. Retrieved 29 October 2013.
  15. ^ "Lifeboat rescuers record busiest July since 2006". BBC News. BBC. 23 August 2013. Retrieved 29 October 2013.
  16. ^ "Heatwave Warning: Danger Of Grass Fires". Sky News. BSkyB. 19 July 2013. Retrieved 29 October 2013.
  17. ^ Bannerman, Lucy (20 July 2013). "Heatwave sparks Britain's worst wildfires for years". The Times. London: News UK. Retrieved 29 October 2013.(subscription required)
  18. ^ "Hot summer helps boost butterflies". BBC Nature. BBC. 16 September 2013. Retrieved 29 October 2013.
  19. ^ Philipson, Alice (30 July 2013). "Warm weather sparks jellyfish invasion". The Telegraph. London: Telegraph Media Group. Retrieved 29 October 2013.
  20. ^ Dutton, Liam (8 August 2013). "Tens of thousands of fish die in recent heatwave". Channel 4 News. ITN. Retrieved 29 October 2013.