The map is a weather chart for midday on 5 August 2003.
The weather map shows an area of high pressure over most of Western Europe. Air is moving around the high in a clockwise direction, bringing a hot, dry tropical continental air mass to the UK at this time. This pattern occurred for much of the rest of the month. High pressure areas usually bring little cloud and warm conditions in summer. This is because the air is sinking and warms as it sinks towards the Earth. Many parts of Europe saw their temperature records broken during this summer, including the UK. A sweltering 39 °C was recorded in Brogdale in Kent on 10 August 2003, a record high which still stands today. Rainfall over much of the UK & Europe was below what is normally expected during the months of June, July and August. The long-lasting high pressure system tended to reduce the amount of rain that fell.
The Satellite image above shows the daytime land surface temperatures in July 2003 compared to July 2001. Areas where temperatures were higher than 2001 are shown in red and areas that were cooler are shown in blue. White areas are unchanged.
The heat wave of 2003 had many impacts. Firstly, many rivers and lakes across the UK suffered very low levels. This was the same across Europe. The River Danube in Serbia fell to its lowest level in 100 years. Bombs and tanks from World War 2, which had been submerged under water for decades, were revealed, causing a danger to people swimming in the rivers. Reservoirs and rivers used for public water supply and hydro-electric schemes either dried up or ran extremely low. The lack of rainfall meant very dry conditions occurred over much of Europe. Forest fires broke out in many countries. In Portugal 215,000 hectares area of forest were destroyed. Extreme snow and glacier-melt in the European Alps led to increased rock and ice falls in the mountains.
About 15,000 people died due to the heat in France, which led to a shortage of space to store dead bodies in mortuaries. Temporary mortuaries were set up in refrigeration lorries. There were also heat-related deaths in the UK (2,000), Portugal (2,100), Italy (3,100), Holland (1,500) and Germany (300).
In addition to the deaths caused by the heat wave people had to cope with;
Summers as hot as 2003 could happen every other year by the year 2050, as a result of climate change due to human activities.
In the UK drinking water supplies were affected in some parts of the UK and hosepipe bans introduced. It was not all bad; many parts of the UK reported increased levels of tourism as people decided to holiday in the UK while the weather was unusually dry and hot. However, agriculture in the UK, was badly affected as many chickens, pigs and cows died during the heat in Europe and crops failed in the dry conditions. This led to higher food prices. It is thought to have cost European farming 13.1 billion Euros. Some railway tracks buckled in the heat. The London Underground became unbearable. Some road surfaces melted. Low river levels prevented some boats from sailing. The London Eye closed on one day as it became too hot in the cabins.
Governments across Europe had to respond to the heat wave. Public water supply shortages occurred in several countries, including the UK and Croatia, which led to a temporary ban on using hose pipes. TV news, internet and newspapers informed the public on how to cope with the heat — drinking plenty of water, wearing cool clothing, and staying in the shade in the middle of the day. Network Rail in the UK imposed speed restrictions for trains when the temperature was above 30 °C. This was to help avoid trains derailing when railway lines might have buckled. Workers around Europe altered their working hours. Some refuse collectors started earlier to pick up rapidly decomposing rubbish from the streets.