Paris is located on a north-bending arc of the river Seine and includes two inhabited islands, the Île Saint-Louis and the larger Île de la Cité which is the heart and origin of the city.
Paris has several prominent hills, of which the highest is Montmartre at 130 metres (426½ ft) above sea level. The highest elevation in the urban area of Paris is 195 metres (640 ft) above sea level in the Montmorency forest (Val-d'Oise département), 19.5 km. (12 miles) north-northwest of the center of
Paris.
The City of Paris (commune) covers 105.397 square kilometres (40.69 mi²), and is only the 113th largest commune in France (out of 36,782), though the urban area ( unité urbaine) (contiguous built-up area) covers 2,723 km² (1,051.4 mi²) (INSEE 1999), or about 26 times as large as the
City of Paris. The metropolitan area (aire urbaine) (built-up area plus the commuter belt) reaches beyond the surrounding Île-de-France région to cover 14,518 km² (5,605.5 mi²) (INSEE 1999), or about 138 times as large as the Paris commune. Excluding the outlying parks of Bois de Boulogne and Bois de Vincennes, the City of Paris is 86.928 square kilometres (33.56 mi²).
Paris is divided into twenty arrondissements. The City's administrative borders have remained largely unchanged since 1860, when Napoleon III and prefect Haussmann doubled the area of the city to 78 km² (30.1 mi²) by annexing the land within the city's ring of fortifications (now the 13th through 20th arrondissements). Several former suburbs such as Montmartre and Auteuil were incorporated at that time. The city limits changed marginally in 1920's reaching 86.9 km². In 1929 the Bois de Boulogne and Bois de Vincennes forest parks were also officially incorporated into the city.
Since meteorological records began in 1873, the lowest temperature recorded in Paris was on December 10, 1879: −23.9 °C (−11.0 °F) in central
Paris and −25.6 °C (−14.1 °F) in the southeastern suburb of Saint-Maur-des-Fossés. The highest recorded temperature in central Paris was 40.4 °C (104.7 °F) in Parc Montsouris on July 28, 1947. The 2003 heat wave caused the deaths of many elderly people with the temperature in central Paris reaching 38.1 °C (100.6 °F) (Parc Montsouris) and 40.2 °C (104.4 °F) at Le Bourget Airport in the northern suburbs. The highest recorded minimum temperature at night in Paris was 25.5 °C (77.9 °F) in Parc Montsouris on August 11 and August 12, 2003.