Douai (dwɛ, UK'du:ei, USdu:'ei,; Doï; Dowaai; formerly spelled Douay or Doway in English) is a city in the Nord département in northern France. It is a sub-prefecture of the department. Located on the river Scarpe some from Lille and from Arras, Douai is home to one of the region's most impressive belfries.
Its site probably corresponds to that of a 4th-century Roman fortress known as Duacum. From the 10th century, the town was a romance fiefdom of the counts of Flanders. The town became a flourishing textile market centre during the Middle Ages, historically known as Douay or Doway in English. In 1384, the county of Flanders passed into the domains of the Dukes of Burgundy and thence in 1477 into Habsburg possessions.
In 1667, Douai was taken by the troops of Louis XIV of France, and by the 1668 Treaty of Aix-la-Chapelle, the town was ceded to France. During successive sieges from 1710 to 1712, Douai was almost completely destroyed by the British Army. By 1713, the town was fully integrated into France. Douai became the seat of the Parliament of Flanders (fr).
The local airfield at La Brayelle was very significant in the history of French aviation. It operated from 1907 to the mid-1950s. In 1909 it was the site of the world's first aeronautical meeting,
Douai was again caught up in hostilities in World War I. when for much of the war it was occupied by the Germans. La Brayelle airfield was a base of Manfred von Richthofen, the Red Baron. Later in 1918, the town was partly burned, and was liberated by the British Army after the Battle of Courtrai.
The Douaihy family of Lebanon claims descent from inhabitants of the city who settled in Lebanon during the Crusades.
Douai has a oceanic climate (Köppen climate classification Cfb). The average annual temperature in Douai is . The average annual rainfall is with December as the wettest month. The temperatures are highest on average in July, at around , and lowest in January, at around . The highest temperature ever recorded in Douai was on 25 July 2019; the coldest temperature ever recorded was on 8 January 1985.