A spell of heavy rain leading likely to accumulations of 25 to 35 mm over a 12 hour period from 3pm.
The warning is valid until 3am on Sunday morning and applies to Donegal, Clare, Kerry and Connacht counties.
A marine gale warning is also in affect.
Met Eireann says there will be some heavy showers on Saturday; localized at first then affecting all areas later in the day leading to some surface flooding and poor visibility.
Some thunderstorms will occur also.
Top temperatures of 15 to 19 degrees in fresh southwesterly winds.
There is a wee bit of better news for Sunday; after earlier predicting a wash-out Sunday is looking like a mainly dry day with some warm sunny spells.
Highest temperatures 17 to 20 degrees in light breezes. Rain will push in from the Atlantic into parts of the west and south late Sunday evening and extend to all parts Sunday night. Very mild with temperatures not falling below 12 to 14 degrees overnight on Sunday.
So far the forecast for Monday, Tuesday and Wednesday is something similar – lovely and warm in the sunshine, but with a possibility of heavy showers.