The catastrophe occurred in August, a month in which many people, including government ministers and physicians, are on holiday. While contingency plans were made for a variety of natural and man-made catastrophes, high temperatures had rarely been considered a major hazard. Most single-family homes and residential facilities were not equipped with central air conditioning. Because of the usually relatively mild summers, most people did not know how to react to very high temperatures (for instance, with respect to rehydration).

France does not commonly have very hot summers, particularly in the northern areas, but eight consecutive days with temperatures of more than 40 ☌ (104 ☏) were recorded in Auxerre, Yonne in early August 2003. In France, 14,802 heat-related deaths (mostly among the elderly) occurred during the heat wave, according to the French National Institute of Health. A public sign in Paris that reads: 'To find a Parisian victim of the heat wave, the city of Paris has established a toll-free number.

Weather underground temperature history