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When we have a warm spell of weather in autumn, you will often hear the term “Indian summer”.

Where does this phrase come from? And what does it mean?

The Met Office Meteorological Glossary, first published in 1916, defines it as "a warm, calm spell of weather occurring in autumn, especially in October and November".

This rather loose definition can be open to interpretation.

Some people claim that an Indian summer cannot come until after the first damaging frost of autumn, or after a severely cold outbreak of weather.

The history of the exact origins of the phrase is complicated and unclear.

Several writers have speculated it may originally have referred to a spell of warm, hazy autumn conditions that enabled Indigenous Americans to continue hunting.

Whatever the origin, the phrase evidently was first was used in the eastern United States, in a letter written by a Frenchman called John de Crevecoeur dated 17 January 1778. In his description of the Mohawk country he wrote, "Sometimes the rain is followed by an interval of calm and warm which is called the Indian summer."

The term was first used in the UK in the early 19th century and went on to gain widespread usage.

The concept of a warm autumn spell was not new to the UK, though. Previously, variations of "Saint Martin's summer" were widely used across Europe to describe warm weather surrounding St Martin's Day, which is 11 November.

We are now in the transition season when the weather changes from the heat of summer to the cold of winter.

The weather in autumn is normally very variable and spells of unusually warm weather are not uncommon. There is no statistical evidence to suggest that such warm spells recur at any particular time each year.

Currently, these are the highest recorded temperatures in the UK in October and November.

Climate change is making severe weather occur more often, last longer and be more severe. How long before these temperature records are broken?

Temperatures are currently well above the mid-September average.

In parts of Scotland and Northern Ireland daytime maximum temperatures are five to eight degrees Celsius above normal.

This weekend will still be quite warm in the northern half of the UK, just not quite as warm as right now. Further south the temperatures will be dropping this weekend. This is due to falling pressure bringing the risk of heavy rain.

Next week the door is wide open to allow Atlantic air to return and bring spells of wet and windy weather. There could be cooler north-west winds late in the month and the weather pattern continues very changeable during the first half of next month.

For our latest thoughts on the next few weeks, read our monthly outlook.