London tornado of 1091

The London Tornado of 1091 is the earliest reported tornado in England, occurring in London on Friday, 17 October 1091. It has been estimated by modern assessment as possibly a T8 on the TORRO scale (roughly equivalent to an F4 on the Fujita scale) making it one of the strongest recorded tornadoes in the British Isles, alongside the 1666 Lincolnshire tornado, although this estimate is based on reports written 30 years later.

The church of St Mary-le-Bow in the city of London was badly damaged; four rafters 26 ft long were driven into the ground so that only 4 ft protruded above the surface. Other nearby churches were demolished by the tornado, as were over 600 mostly wooden houses. For all the damage, there were just two known fatalities in a population of about 18,000. The tornado is mentioned in chronicles by Florence of Worcester and William of Malmesbury, the latter describing it as "a great spectacle for those watching from afar, but a terrifying experience for those standing near".