Met Office warns of continued heavy rain and local flooding across much of the UK

Heavy rain is set to drench much of the UK over the next few days, prompting a Met Office yellow warning for parts of south Wales and raising the risk of localised flooding and travel disruption.

The warning for rain in south Wales is in place through 23:00 BST on Wednesday, and forecasters said a slow-moving weather front is expected to stall across parts of Wales and northern England. Widespread falls of 30-40mm are likely, with isolated totals of 70mm in the hardest-hit locations and 100-150mm forecast over some hills as new areas of low pressure develop and the rain becomes more intense through the weekend.

The persistent south-westerly winds that have brought a succession of Atlantic low-pressure systems already delivered near-record September rainfall in parts of the country. Cardiff, for example, has recorded more rainfall so far in September than in the whole of the summer, and other areas of Wales, Northern Ireland, northwest England and southern England have seen significantly above-average totals.

The Met Office and local authorities warned that the combination of heavy, sustained rain and saturated ground could lead to localised flooding, surface water accumulation and difficult driving conditions in affected areas. Transport disruption is possible on major routes and local roads, particularly where waterways run close to transport corridors.

Northern Ireland lies close to the stalled front and is likely to be wet in the far southeast, although forecasters said it was unlikely to be as consistently wet there as in recent weeks. Scotland will see wet and windy weather initially, clearing to more showery conditions with a drop in temperatures; the Scottish mountains may see a touch of wintry precipitation on the very highest tops by the weekend as cooler air arrives.

In contrast, parts of south-east England, the Midlands and East Anglia are forecast to warm markedly in the short term, with temperatures potentially reaching about 26C in some locations on Friday before outbreaks of rain and cooler air spread eastwards over the weekend.

Local authorities and the Environment Agency urged residents in vulnerable areas to monitor flood alerts and warnings, take common-sense precautions where floodwater is possible, and avoid driving through standing water. Emergency services said they were prepared to respond to incidents, while transport operators warned that timetables and road conditions could be affected.

Forecasters indicated a change to drier weather is expected next week as high pressure builds back across the UK. That settled spell is likely to bring more sunshine for many areas but temperatures are expected to be a little below average, with the possibility of rural overnight frost and spots of early-morning mist or fog where winds become light.

The Met Office advised people to check the latest local forecasts and warnings as the situation can evolve, particularly in areas where slow-moving fronts can intensify rainfall over a short period. Residents and travellers were reminded that conditions can vary sharply over short distances, especially in hilly and coastal terrain.

Weather services said the current wet spell results from a series of Atlantic systems driven in by persistent south-westerly winds, and while the most intense rain is expected to ease once high pressure returns, the coming days remain the period of greatest risk for flooding and travel disruption.