The heat wave led to health crises in several countries and combined with drought to create a crop shortfall in parts of Southern Europe.

[4][5] The predominant heat was recorded in July and August, partly a result of the western European seasonal lag from the maritime influence of the Atlantic warm waters in combination with hot continental air and strong southerly winds.

[citation needed] In France, 14,802 heat-related deaths (mostly among the elderly) occurred during the heat wave, according to the French National Institute of Health.

[6][7] France does not commonly have very hot summers, particularly in the northern areas,[8] but eight consecutive days with temperatures of more than 40 °C (104 °F) were recorded in Auxerre, Yonne in early August 2003.

While contingency plans were made for a variety of natural and man-made catastrophes, high temperatures had rarely been considered a major hazard.

[citation needed] The catastrophe occurred in August, a month in which many people, including government ministers and physicians, are on holiday.

During the heat wave, temperatures remained at record highs even at night, breaking the usual cooling cycle.

Many blamed Health Minister Jean-François Mattei for failing to return from his vacation when the heat wave became serious, and his aides for blocking emergency measures in public hospitals (such as the recalling of physicians).

"These thousands of elderly victims didn't die from a heat wave as such, but from the isolation and insufficient assistance they lived with day in and out, and which almost any crisis situation could render fatal.

Although research established that heat waves represent a major threat for public health, France had no policy in place.

Until the 2003 event, heat waves were a strongly underestimated risk in the French context, which partly explains the high number of victims.

In addition to a major effort to issue warning messages in time, the plan includes measures such as cooling rooms at senior centers, replacing tarmac at playgrounds with more heat reflective materials, and mandatory insulation in construction regulation.

This reflects a growing awareness of the benefit of an integrated response to risks like heatwaves, compared to stand-alone technologies and projects and greater attention paid to green and blue infrastructure in city planning.

[16][17] Five percent of Portugal's countryside and 10% of the forests (215,000 hectares[7] or an estimated 2,150 km2 (830 sq mi)), were destroyed, and 18 people died in the flames.

Due to a number of deaths, the UK government released its Heat Health Watch system, issuing warnings if temperatures rise above 30 °C in the day and 15 °C at night.

[38] The tarmac melted on part of the M25 between Junctions 26 and 27,[39] and rails buckled from expansion on the hottest day in England in 13 years, while two teenaged boys drowned while trying to escape the excessive heat.

By mid-August, the grapes in certain vineyards had already reached their optimal sugar content, possibly resulting in 12.0°–12.5° wines (see alcoholic degree).

The heatwave made Hungary fare extremely well in the Vinalies 2003 International wine contest: a total of nine gold and nine silver medals were awarded to Hungarian winemakers.

A seasonal current of the central Mediterranean Sea, the Atlantic Ionian Stream (AIS), was affected by the warm temperatures, resulting in modifications in its path and intensity.

Losses of over 1% of GDP were recorded in areas with high exposure to heat and showing a large share of outdoor work.