BBC Weather's monthly outlook

For the month of September, the BBC Weather outlook predicts a period of significant unsettled weather, beginning in late August and extending into early September. Expect heavy rain and thunderstorms to be common during this time, with high pressure gradually building across Europe towards mid-September. This shift in weather patterns is expected to bring drier conditions to some regions, predominantly the south, although the north will likely remain cooler.

As the weekend approaches, high pressure will make its way across the UK from the west, resulting in a drier spell for most. Temperatures will hover near the average for the southern UK and slightly below average in the north, with cooler nights. During the first half of the coming week, an easterly to southeast to southwesterly wind flow will be present, which will drive temperatures higher, potentially peaking on Wednesday.

However, this warming trend will also allow low pressure systems and frontal weather to approach from the southwest, leading to thundery outbreaks and a Spanish plume-type system. On Monday, expect a generally dry day, with showers potentially starting in the southwest later in the day and becoming more widespread on Tuesday. Thunderstorms are likely to develop across parts of England and Wales, with further heavy rain and lightning possible through Thursday.

The latter part of the week is expected to be unsettled, with strong winds and a high chance of localized flooding.

Conditions are forecast to remain unsettled during the remainder of the month, with low pressure systems likely to pass close to or over Scotland. This will bring bouts of rain, sometimes heavy and thundery, alongside occasional strong winds. Although there may be short-lived spells of calmer and drier weather, precipitation is likely to remain intense enough to pose a risk of local flooding.

Despite the rain, temperatures are expected to be variable from day to day but will on average stay near or slightly above average for the week. The dominance of Atlantic weather systems is expected to continue into the first week of September, leading to further periods of wet and windy or showery weather, interspersed with brief drier and sunnier intervals.

The north and west are likely to experience wetter conditions than the south and east, while temperatures are more likely to remain near or slightly above normal throughout the period.