Met Éireann is warning of gusts of up to 130 kilometres an hour in counties Galway, Mayo and Donegal from tomorrow morning.
The Status Orange warning is in operation for Galway and Mayo from 5am to 1pm Friday and for Donegal from 9am Friday to 6am Saturday.
The issue is caused by the high winds now battering large parts of Northern Ireland - there are now seven issues right across the country.
"Bear in mind that there is a risk of coastal flooding on Atlantic coasts in particular: only drive through water if you know it's not too deep for your auto".
Strong to near gale southwest to westerly winds, with gales or strong gales near the coasts, will slowly ease overnight.
Storm Erik was named by Irish forecaster Met Eireann on Thursday.
The Met Office warned that travel delays throughout the day were very likely, with the risk of fallen trees blocking roads and railways and high winds closing bridges and ferry routes.
Meanwhile, a second weather warning for strong winds extends over large parts of central and southern Scotland.
Torrential rain and brutal gusts reaching 70mph have been forecast to hit Britain over the weekend.
There will be a spell of heavier rain accompanying the strong gusts with snow over the tops of the Pennines.
It will remain unsettled and blustery through Saturday.
Temperatures will be above average but it will feel cooler in the winds. Top temperatures 6 to 8 degrees in light variable breezes.