The third named storm of the autumn, Conall, has brought more disruption to the UK, with trains cancelled in parts of southern England on Wednesday and the Met Office warning of delays on roads and the potential for power cuts.

Up to 40mm of rain fell overnight in parts of south and south-east England and another 5-8mm was expected during the day. The Met Office issued a severe weather warning for London and areas of Essex, Kent, Surrey and West Sussex.

While the Met Office did not name the storm, its partner the Dutch forecaster KNMI did so because Conall was expected to bring strong winds to the Netherlands.

On Wednesday morning there were no trains between Ascot in Berkshire and Aldershot in Hampshire, and part of a line was blocked on the Isle of Wight. There was also train disruption across the Thameslink, Gatwick Express and Southern networks.

Farther west, the impact of last weekend’s storm, Bert, meant there was disruption to trains between Hereford and Newport in south Wales and in the south Wales valleys.

Almost 100 flood warnings remained in place for England and Wales and there was one severe flood warning – meaning danger to life – for the River Nene at the Billing Aquadrome in Northamptonshire.

The Environment Agency said the situation on the Nene “remains hazardous”. It said: “There is danger to life. Keep yourself and your family safe. Severe flooding is expected to continue. Please stay evacuated from the area.”

Storm Bert left more than 500 homes and businesses in England and Wales flooded, turned roads into rivers and brought winds of more than 80mph.

By early afternoon on Wednesday, Conall had largely departed the UK. Rain totals from 10pm on Tuesday to noon on Wednesday included Calbourne on the Isle of Wight at 43.3mm; Warnford, Hampshire at 37.4mm; and Harbertonford, Devon at 37.1mm.

A Met Office spokesperson said: “It will be bringing more significant impacts to the Netherlands. We didn’t name this one – it’s more of a glancing blow with some rainfall for us.”

On Thursday frost and fog is due to slowly clear from most areas to leave a dry, chilly day with some sunshine. It is set to become cloudier and windy in the west with some patchy rain.