Heavy rain is also forecast just a couple of weeks after Ciarán caused flooding on the south coast.
Multiple weather warnings are in place, including the Met Office saying there is a potential danger to life due to ‘fast-flowing or deep floodwater.’
It added that homes and businesses could also face damage due to the weather.
You can check out how Storm Debi is progressing across the UK by watching the tracker video above.
The strongest winds are forecast to hit south-east Northern Ireland, north-west England and north-west Wales, according to the Met Office.
They could reach around 65mph inland, or as fast as 80mph in certain coastal areas and on higher ground.
And the agency has issued a yellow weather warning for wind and rain for the whole of Northern Ireland which started at 3am today and lasts until 2pm.
Serious flooding hit Northern Ireland and the Republic of Ireland at the end of last month, with Co Down, Co Louth and Co Wexford among the areas most impacted by Storm Ciarán.
Met Éireann, the Irish meteorological agency, has issued a status red wind warning to five counties in the centre and west of the country, while every other county falls under either a status orange or status yellow warning.
The counties warned of ‘severe and damaging gusts’ from the new named storm last night and into today include: Carlow, Dublin, Kildare, Kilkenny, Laois, Longford, Louth, Meath, Offaly, Westmeath, Wicklow, Clare, Kerry, Limerick, Tipperary and Galway.
The Met Office has issued a separate yellow wind warning for a large part of Wales and a lot of England north of Nottingham, which has been in place from 4am today and will last until 6pm this evening.
Flying debris and large waves in coastal areas could pose a danger to life. Transport is also likely to be affected.
A separate weather warning for rain is in place for north-east Scotland today with a ‘small chance’ of danger to life and damage to buildings because of flooding.
Met Office chief meteorologist Jason Kelly said: ‘Storm Debi will develop quickly and bring potentially very strong and damaging winds to parts of the Republic of Ireland, which is why Met Éireann has decided to name the system.
‘The strongest winds are expected to affect parts of the Republic of Ireland early on Monday, possibly coinciding with the morning commute, before then affecting parts of north Wales and northern England into the afternoon.’
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