UK set for coldest night of autumn so far

After a spell of unusually warm weather, UK temperatures are set to tumble with the coldest night of autumn so far arriving by midweek.

Wednesday night will bring the first frost of the season to some places, as colder air arrives from the Arctic.

In some areas, minimum temperatures could be just a degree or two above freezing by dawn on Thursday.

Along with the plummeting temperatures, some much-needed rainfall is on the way for England and Wales.

So far this autumn, the jet stream - which determines what sort of air mass affects the UK - has been sitting to the north.

This has allowed mild south or south-westerly winds to flow, particularly across the southern half of the British Isles.

This week, however, the jet stream will start to sink further south, allowing the winds to turn more northerly and introduce a colder air mass.

While it will feel significantly colder compared to recent weeks, especially in the south, temperatures will actually be near normal for the time of year or perhaps just a little below.

Afternoon highs on Wednesday will be around 12C to 14C in Northern Ireland and Scotland and 14C to 16C in England and Wales.

Whilst the northern half of the UK has already seen temperatures near the seasonal average this month, it has consistently been several degrees above average in the south, with somewhere reaching above 20C every day since 11 June.

By the overnight hours, temperatures will be unseasonably low with a noticeable chill first thing on Thursday.

Minimum temperatures at dawn will be around 5 to 7C for most places, but the coolest areas in northern and eastern England as well as eastern Scotland could be just a degree or two above freezing.

A touch of frost is likely on grass and car windscreens here.

In addition to the autumn chill, much-needed rain will spread across England and Wales from midweek.

Wednesday will start cloudy and wet as a frontal system slowly drifts eastwards.

Whilst sunshine will return to many places in the afternoon, rain is expected to linger for most of the day in East Anglia and the far south-east.

Southern and eastern England, where it has been especially dry lately, could receive around 20 to 30mm.

This would equate to up to half a month's rainfall in just 24 hours.

Nearly three quarters of England and all of Wales are still in drought.

The Environment Agency has previously said that 20% more rainfall than average is needed for at least seven months before all areas will be out of drought status.