MAYO communities susceptible for flooding have been placed on alert.
Met Éireann's Head of Forecasting Evelyn Cusack has said the south and west coasts will be most at risk of flooding tonight and tomorrow as Storm Callum passes over the country.
Ms Cusack said high tides, strong gales and winds are expected with south-easterly winds up to gale force 8 or 9 gusting to storm force 9 overnight.
Met Eireann's forecast for the Connaught region is as follows:
“It will become very windy tonight as south to southeast winds increase strong to gale force. Winds will be stronger near the coast with strong gale force winds and severe or damage gusts. There will be heavy rain at times also.
“Tomorrow will remain very windy in western parts on Friday morning and for a time during the afternoon with further severe gusts near the coast. Winds will ease somewhat elsewhere becoming fresh to strong southerly.
"Rain will clear quickly during the morning and it will be dry for a time but later in the afternoon outbreaks of rain will develop again.
“The strong southerly winds will gradually ease on Friday night. Rain will clear the east coast early in the night and it will become dry for a time but more rain will spread from the south to most areas by Saturday morning. Lowest temperatures of 8 to 12 degrees.
“On Saturday winds are expected to be mostly light everywhere. It will be a wet day for many with outbreaks of rain throughout the day, heavy and persistent at times. On Saturday night the rain will clear most areas and clear spells will develop. Lowest temperatures of 5 to 8 degrees in westerly breezes.
“At the moment Sunday is looking mainly dry and bright with just scattered showers and temperatures of 10 to 14 degrees in westerly breezes.
“The weather for next week will continue unsettled with further spells of wet and windy weather.”
A meeting of the National Emergency Coordination Committee is taking place in Dublin this afternoon amid fears over the impact of the storm.
There are concerns some schools may not be in a position to open tomorrow in the aftermath of Storm Callum.