2013 heatwave in Ireland and the United Kingdom

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 at Heathrow and Northolt. Following a brief period of cooler weather at the end of July, temperatures temporarily rose again, peaking at 34.1°C on 1 August in the United Kingdom, the warmest the country had seen since July 2006, and 31.0°C in Ireland. At 19 days, the July heatwave was the longest continuous period of hot weather in the UK since August 1997.

However, in the general sense, Britain did not have an overall exceptional summer; the country experienced cool low pressure systems brought by an unseasonably low latitude by the jet stream for the 6 summers previous, which made the summer of 2013 more "welcome" and feel warmer than other summers. The historical records suggests "Using the CET record (for June, July & August), the average TEMPERATURE by that measure was=16.3degC (Provisional): neither June nor August was exceptionally WARM, so this value does not 'rate' too highly when set against other very WARM summer seasons." With June being a cool month and August being an Average month, in terms of temperatures the English Central summer temperature ended up being on the average side set up against previous summers since the CET series began in 1659.

Timeline

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, and Scotland and Northern Ireland expected to avoid the warmest weather. In the following week temperatures reached 29.7°C on the south coast and climbed to 30°C in Northern Ireland, the highest temperature seen there since 2006.

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 for the day and 15°C for the night. Once the threshold temperatures have been exceeded, the region is categorised according to risk and impact on health and social services. On 12 July, the Met Office released heat wave alerts across much of England: the West Midlands, North East and North West regions were given a level one warning, the lowest of four the Met Office uses; the East Midlands, the East of England, Southeast England, London and Southwest England regions given level two; and Yorkshire and the Humber were placed in the level three category. The highest category, level four, indicating a national emergency, was not used.

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.

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. 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. In some places, 1 August was actually warmer than all of the days in July. London Heathrow recorded 34.1°C, which exceeded the previous record of 33.5°C which was recorded on 22 July. By 2 August however, temperatures began to return to normal.

Responses

Despite the heat there were no plans to introduce a hosepipe ban, with reservoir levels remaining at the expected level.

A number of MPs supported an early-day motion that called for a workplaces to have a maximum temperature limit of 27°C for those doing "strenuous work" and 30°C for everyone else.

Impacts

Ireland

There was a large increase in the number of calls to lifeguards. Thirteen people drowned in the month.

The heat wave boosted the Irish economy, with consumers spending an extra €30 million during the summer.

United Kingdom

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.

Emergency services

The heat wave led to rises in both the number of calls to the emergency services and admissions to A&E departments. 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. The London Fire Brigade reported having to deal with double the number of grass fires in the capital compared to the previous year. Wildfires were also reported in Epping Forest in Essex, the Dorset coast, the valleys of southern Wales and Tentsmuir Forest in Scotland.

Economic

The heatwave had positive impacts on the UK economy, with retail sales up by 3.0% compared to July 2012, producing the best monthly set of figures since 2006. The British Retail Consortium also cited Andy Murray's success at Wimbledon, the commencement of the 2013 Ashes series and the birth of Prince George of Cambridge as contributory factors to this increase. In particular, the warm temperatures increased sales of DIY and gardening equipment and barbecue-related items and foods, with Waitrose reporting and jump in sales of 116% for barbecues, 450% in charcoal and 165% for outdoor furniture in the first week of the heatwave. The high volume of retail sales pushed up the value of the pound.

More than 120,000 people visited Bournemouth beach. Tourism figures showed rises in some parts of Wales, especially in caravan and camping parks and outdoor monuments, although self-catering operators and museums saw a drop in numbers.

Ecological

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

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.