Ali has begun to make itself felt across Northern Ireland and parts of Scotland and England with 60mph winds as the first named storm of the season arrived in time for the morning rush hour.
Travel disruption, power cuts and flying debris are possible as the storm sweeps through, with severe gales of up to 75mph and heavy rain forecast for a large part of the UK.
There is also potential for damage to buildings, fallen trees, travel cancellations, road closures and large waves in coastal areas.
As Ali rolled in on Wednesday morning the Met Office updated its amber weather warning of wind, saying there is now a high likelihood of impacts across a swathe of the country.
Gale-force gusts began to be recorded on the Galway coast as heavy rain moved in, although the worst of the weather was not expected to be seen until later on Wednesday morning.
The amber warning covers Northern Ireland, northern parts of England and southern Scotland until 6pm, while a further yellow warning of winds up to 60mph covers the rest of Scotland, Yorkshire and northern parts of Wales.
Met Office meteorologist Mark Wilson told the Press Association: “Storm Ali is already bringing some pretty heavy rain across Northern Ireland and south-west Scotland and is just starting to creep into north-west England.
“In terms of wind strength, the speeds are coming up, with a gusts of just over 60mph in the west of Ireland.
“Around eight, nine and ten o’clock winds will really start ramping up and go further still.”
The worst of Ali’s weather is forecast to be in the north, although areas outside the official weather warnings are unlikely to escape wet and windy conditions.
While southern parts of England and Wales could reach continued unseasonable highs of up to 24C (75F), it will feel cooler due to the strong winds, Mr Wilson said.
The unsettled weather is due to last right through the week, but an improvement is expected early next week as drier weather is set to take hold.
Ali is first on the storm names list for 2018-19 announced by the Met Office and Met Eireann, which has run the Name Our Storms scheme for four years.
The season’s names have been compiled from a list of submissions by the public, choosing some of the most popular names and also selecting those which reflect the nations, culture and diversity of the UK and Ireland.