The UK Met Office has warned that lives could be in danger in parts of the UK as Storm Bram brings heavy rain and strong winds.

Amber weather warnings – meaning there is “potential risk to life and property” – were in place for areas of south Wales and south-west England on Tuesday morning.

An amber warning for north-west Scotland was coming into force from 4pm until midnight, where winds as high as 90mph were expected.

By 7am on Tuesday there were more than 300 flood warnings or alerts across England, Wales and Scotland, meaning flooding was either expected or possible.

Drivers were warned that they faced difficult conditions and possible road closures, and delays were expected on some train lines.

The amber rain warning included parts of south Wales and the south-west of England, mostly covering Dartmoor in Devon.

Meanwhile, every county in the Republic of Ireland will be under an orange weather warning at some point on Tuesday, according to upgraded advisories from Irish forecasters.

After a week of persistent rain, the Irish forecasting agency Met Éireann said soil across the country was already highly saturated and many rivers were approaching bank-full conditions, so any additional rainfall was likely to result in surface and river flooding.

Met Office forecasters said 50-75mm of rain was expected across much of the two areas covered by the amber rain warning, most of which will fall in about nine hours.

A few exposed locations could have about 100mm of rain, accompanied by strengthening southerly winds, which the Met Office said could exacerbate conditions.

It said homes and businesses were likely to be flooded, causing damage to some buildings. Fast-flowing or deep flood water was likely, causing danger to life.

Delays and some cancellations to train and bus services were likely, it said, and spray and flooding would probably lead to difficult driving conditions and some road closures.

The Met Office said there was a good chance some communities would be stranded by flooded roads and there could be power cuts and loss of other services.

Great Western Railway said it expected flooding to “significantly affect” its services on Tuesday.

Devon county council said high winds and heavy rain were causing difficult travel conditions. It said: “Please take care, expect fallen trees, debris and flooding, especially near rivers and the coast.”

The Met Office said there was potential in north-west Scotland for large waves and beach material being thrown on to sea fronts, coastal roads and properties

It said roads, bridges and railway lines could close and there could be delays and cancellations to bus, train, ferry services and flights. Power cuts could occur and affect other services, such as mobile phone coverage

Damage to buildings and homes was possible, with roofs blown off and power lines brought down and flying debris could result in a danger to life, it said.

Transport Scotland said there could be disruption to road, rail, air and ferry travel. The Scottish transport secretary, Fiona Hyslop, urged people to plan ahead if they needed to travel.

Extreme rainfall is more common and more intense because of human-caused climate breakdown, particularly in Europe, most of Asia, central and eastern North America, and parts of South America, Africa and Australia. Warmer air can hold more water vapour.

Flooding has most probably become more frequent and severe in these locations as a result but is also affected by human factors such as the existence of flood defences and land use.