The low-pressure weather system is expected to bring strong winds to Ireland and southern parts of the United Kingdom from Friday afternoon to Saturday morning.
The country's Met Office has issued amber warnings as wind gusts are expected to reach a potentially damaging 80mph.
Ireland's west and southeast counties are under yellow storm warnings for Friday from 11pm to Saturday at 9am.
The warning is due to start at 6pm on Friday and expire at 6am on Saturday.
Storm Hannah is due to make its way out of the United Kingdom on Saturday, bringing more settled weather on Sunday.
Be prepared this weekend - the tail end of Storm Hannah could hit East Anglia, bringing heavy rain and strong winds..
Status Orange Wind Warning for Tipperary and Waterford is also in place from 10pm tonight until 2am tomorrow morning.
Early on Friday night will west and will be very windy or stormy in Munster and Connacht, especially in coastal areas with very strong, gusty west to northwest winds.
Irish forecaster Met Éireann said County Clare could expect gusts up to 95mph (150km/h) on Friday night.
Its severe weather team met today to plan for an eventualities and issue an warning to people.
The Irish meteorological service warned: "With many trees now in leaf, this system has the potential to result in trees down, leading to power outages and risky driving conditions".
"Storm Hannah will push across the country tomorrow evening and tomorrow night", he said.
There will be more rain tomorrow afternoon.
Eventually the winds "will ease" but the rain will "tsar its time to clear", Ms Nasir forecasted.
Ms Keith-Lucas added: "We have got some heavy scattered showers across northern Croatia and into northern parts of Italy". It will clear later with scattered showers following.
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