Warm start to week to make way for wetter and windier conditions

Changeable autumnal conditions are set to continue through this coming week, with spells of wetter and windier weather developing at times.

Monday will bring a short-lived burst of warmth and sunshine before temperatures drop to levels more typical for September later in the week.

A strengthening jet stream will bring deeper, low-pressure systems as the week goes on, with the potential for minor disruption towards next weekend.

Higher pressure looks set to build again for the end of the month, but prospects of a late-September heatwave remain uncertain.

The jet stream is a ribbon of fast-moving air high in the atmosphere, around six miles above our heads, and its shape, speed and position help dictate what type of weather we experience.

During the start to the week, the jet stream will be relatively weak and loop to the north of the UK, allowing higher pressure to develop and a warm south-westerly airflow to take hold.

Later, the jet stream will take on a more southerly path, flowing faster and straighter towards our shores. This will mean lower pressure will form, bringing rain and brisk winds at times, and temperatures will drop.

Monday will be the warmest day of the week, with the air coming in from a south-westerly direction.

Many areas will stay fairly cloudy, with some rain around coasts and hills in the west. Despite this it will feel warm and rather humid, with temperatures climbing above 20C in many places.

Where the sun does break through, in central and southern parts of England, temperatures could reach as high as 26C.

By Thursday the winds will turn more westerly or north-westerly, bringing a fresher air mass and a cooler feel to the weather. Temperatures by this stage will reach around 14 to 16C in Scotland and Northern Ireland, and 17 to 20C in England and Wales.

Forecasts are showing that areas of high pressure should have more influence on the weather for the last week of September. This may mean longer dry interludes and the chance of returning to above-average daytime temperatures, but the degree of temperature rise will depend on the positioning the high pressure relative to the UK.

While long-range forecasting is fraught with uncertainty and details are subject to change, there is currently nothing to indicate that a heatwave is on the cards.

Indeed, as autumn advances and the nights become longer, high pressure overhead could lead to some rather chilly mornings.