What is an ‘Indian summer’?

After a warm, dry, sunny summer, the fine weather is continuing this week with temperature expected to reach 28 to 29 °C in the southeast on Wednesday and Thursday.

Many media reports are calling this an ‘Indian summer’, however according to the Met Office’s Meteorological Glossary, it’s a little too early in the year. An Indian summer is defined as a warm, calm spell of weather occurring after the first frost in autumn, especially in October and November.

William R Deedler, Weather Historian at the United States National Weather Service, describes it as “any spell of warm, quiet, hazy weather that may occur in October or even early November”.

The origins of the term Indian summer are uncertain, but several writers suggest it may be have been based on the warm, hazy conditions in autumn when native American Indians chose to hunt. The earliest record of the use of the term is in America at the end of the 18th century. Although William R Deedler also refers to a reference by a French man, John de Crevecoeur, in 1778:

“Sometimes the rain is followed by an interval of calm and warmth which is called the Indian Summer; its characteristics are a tranquil atmosphere and general smokiness. Up to this epoch the approaches of winter are doubtful; it arrives about the middle of November, although snows and brief freezes often occur long before that date.”

The term was first used in the British Isles at the beginning of the 19th century, but there is no statistical evidence to show that such a warm spell tends to recur each year. The warmest recorded temperatures in the UK in October and November are 29.9 °C on 1 October 2011, in Kent, and 21.1 °C on 2 November 1938, in Essex and Suffolk.

For the latest weather forecast go to www.metoffice.gov.uk/weather

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3 Responses to What is an ‘Indian summer’?

  1. Why does the MetOffice say autumn starts on 1st September when the solstice is on 21st September? Is it purely for convenience?

    • Dave Britton says:

      Hello Alan

      There are a number of ways of defining seasons, see http://www.metoffice.gov.uk/climate-change/guide/impacts/horticulture. The Met Office uses meteorological seasons and autumn is defined as 1 September to 30 November.

      This method of defining seasons was established in 1780 by the Societas Meteorologica Palatina, an early international organization for meteorology, defined seasons as groupings of three whole months. Ever since, professional meteorologists all over the world have used this definition. Therefore, for the Northern hemisphere, spring begins on 1 March, summer on 1 June, autumn on 1 September, and winter on 1 December. For the Southern hemisphere, spring begins on 1 September, summer on 1 December, autumn on 1 March, and winter on 1 June.

      I hope this clarifies the way meteorological seasons are defined.

  2. jbenton2013 says:

    What is an Indian Summer?

    An Indian Summer is something the Met Office completely failed to predict for 2013.

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