Monthly Outlook

Unsettled weather is expected to dominate through the first half of September, with heavy rain, thunderstorms and strong winds possible at times.

From mid-September onwards, high pressure may build and bring a return to drier and warmer conditions.

Remaining unsettled

Over the weekend a couple of low pressure circulations and complex frontal systems will bring periods of rain or showers. It will be rather windy at times, especially across southern parts of England and Wales.

A few heavy and gusty downpours are possible, with a risk of thunderstorms more likely across England and Wales than Scotland and Northern Ireland.

A disturbed weather pattern will continue through the coming week, with further low pressure systems and associated fronts crossing the UK. These are going to bring bouts of rain, heavy and potentially thundery at times, occasionally accompanied by strong and gusty winds.

Transitory high pressure ridges should bring calmer and drier spells with some sunshine, although a few scattered showers will still be possible. High pressure could give south-eastern areas a better chance of a couple of drier days.

Overall, most areas should be wetter than average. Temperatures are going to vary from day-to-day, but on average they are more likely to be near or slightly above normal with warmer conditions in the southern UK, especially later in the week.

Cooler overall and still changeable

Atlantic weather systems should continue to dominate conditions into the second week of September, with low pressure and frontal systems tracking near or across the UK, so further periods of wet and windy or showery weather look most likely.

Short-lived drier and sunnier spells should occur in-between, especially in the southern and eastern UK where conditions may be less wet overall than the north and west. It is likely to turn cooler, with temperatures likely to be closer to normal.

By the end of the week there is a possibility of a change beginning. High pressure could start to build again across continental Europe and towards the UK. This might push some warmer air northwards towards the UK, with some drier conditions possible, particularly across southern parts of the UK.

Turning drier and warmer

Although the outlook becomes unclear after mid-September, there are some signs that high pressure could build across the UK, leading to longer drier periods, with rainfall amounts below normal in many areas, or at least near average.

It could be wetter the further north you are, with Scotland most susceptible to occasional frontal systems moving across.

Temperatures should increase, with above-average warmth most likely overall. A further boost to the temperature may come later in the month if high pressure shifts to the east and draws in more of a south-east or southerly flow.

Eventually this might also allow low pressure systems to approach and bring a return to less settled weather, but that's very speculative at the moment.

In Tuesday's update, will review the chances of the unsettled spell being replaced by drier conditions around mid-month onwards.