by Philip Eden

Mild southwesterly winds prevailed throughout early October but last Thursday (the 12th) the wind backed southerly, delivering air of Mediterranean origin to much of the country, and this provided an additional boost to temperature levels. That afternoon the sun broke through the clouds in East Anglia, the East Midlands, Lincolnshire and Yorkshire, and these brighter areas the mercury climbed to 20C at several sites, approaching 21C at Marham, near King's Lynn, at Coltishall, near Norwich, at Skegness, and in Leeds.

Friday was an even better day with practically uninterrupted sunshine over much of England and Wales. The temperature climbed rapidly to reach 20-22C over a wide area, and 23C at Gravesend in Kent, Chelmsford in Essex, St Albans in Hertfordshire, and at Torqay in Devon. And on Saturday, despite increasing amounts of cloud, 25C was recorded at Northolt in northwest London. Such figures are 6 to 9 degC above the long-term average for mid-October.

Most of us like to call such a short spell of unseasonable warmth in autumn an "Indian Summer". The expression is borrowed from North America - not the Indian sub-continent - and lexicologists tell us that the first known reference dates from the early 18th century. The indigenous population of the eastern seaboard of the USA used to rely on extended periods of dry, sunny, relatively cool weather at this time of the year to complete the harvest and put together stores of fruit, berries and nuts to see them through the long snowy winter. The early colonists soon discovered that the region's summers were excessively hot and humid, and they would have noted the contrast between the enervating summers and the pleasant autumns when hard physical work could be undertaken without fear of heatstroke.

British Indian Summers may be characterised by unusually warmth rather than comfortable coolness, but many people are surprised just how hot October days can be. The month's highest ever temperature in the UK was 29.4C at March, Cambridgeshire, on the 1st in 1985. Mid-month heatwaves brought temperatures of 24-25C in both 1990 and 1997.