The Taoiseach says he's shocked at the extensive damage caused by wild weather in Inishowen.
Around 200 homes were destroyed while roads and bridges were washed away following heavy rainfall on Tuesday night.
Met Eireann says further heavy rain is forcast for Donegal, Sligo, Leitrim, Mayo and Galway until tomorrow evening.
The Government says it will provide emergency funds to affected households in Donegal.
In a video message Leo Varadkar says help is available: