Rain to return this week with chance of thunderstorms and flooding

This week, rain is forecast to return to the UK, accompanied by the potential for thunderstorms and localized flooding. Showery conditions may re-emerge by Tuesday, but more widespread and persistent rain is expected from Wednesday onwards, originating in the south. While the rain will be beneficial for parched areas of the UK, it will take considerable rainfall to alleviate drought conditions.

As warmer air moves in, mid-week temperatures could climb close to 30C (86F) in certain regions. However, drier weather will continue into Monday for the majority of locations. On Tuesday, low pressure from the southwest will introduce showery weather to parts of southern England and south Wales. By Wednesday, downpours will become more widespread across England, Wales, and Northern Ireland, with Scotland likely to remain largely dry.

There may be some heavy and thundery bursts. From Wednesday through Friday, the risk of torrential downpours, hail, and thunderstorms will increase, particularly in southern England and Wales, where heavy rain on dry, hard ground could lead to localized flooding. Although this week's rainfall is welcome and will help raise river levels and soil moisture, it will take time for catchments and reservoirs to fully recover.

Droughts generally do not end quickly following a single period of rain. According to the British Geological Survey (BGS), significant, cumulative rainfall over an extended period is necessary for a drought to officially conclude. Currently, only eight out of the 35 groundwater sites surveyed by the BGS across the UK exhibit notably low levels (23%).

Despite the return of wet weather this week, warmer air from southern Europe is anticipated to return. By Wednesday, temperatures in Scotland and Northern Ireland are expected to reach around 20C, while England and Wales may experience highs of 28 or 29C in the southern regions. However, this heat is likely to be short-lived, and temperatures are unlikely to reach heatwave levels again before the end of August.

Longer-term, some computer models suggest that higher pressure could build into the second week of September, potentially bringing warmer air back to the UK. The warmest temperatures are expected across southern England. Keep monitoring the monthly outlook for the most recent insights on the long-range forecast.