Friday will begin dry and bright across much of the country.
However, rain and drizzle will develop in Atlantic coastal areas of the west and north by early afternoon.
The rain will become more persistent across Connacht and Ulster in the evening but will be patchy elsewhere with southern portions of Munster and Leinster staying mainly dry.
An increasingly humid day with highest temperatures ranging 17 to 23 degrees, warmest in Munster and south Leinster.
Winds will be moderate to fresh southwest in direction and will increase strong at times near Atlantic coasts.
Friday night meanwhile will be mostly cloudy with spells of rain across west Munster, Connacht and Ulster.
Rain will be lighter and patchier elsewhere with good dry periods in places.
Mist and fog will form, especially on hills and along the coast.
Very mild and humid overnight with minimum temperatures of 13 to 16 degrees in moderate or fresh south westerly winds.
It will be warm and humid on Saturday.
There will be a good deal of cloud in northern and western areas with intermittent rain and drizzle, persistent at times in coastal fringes.
However, there will be good dry periods elsewhere with some sunny spells, the best of these in southern and eastern counties.
Mist and fog will affect some coasts and hills also. Highest temperatures of 18 to 24 degrees, warmest across east Munster and Leinster.
Winds will be moderate to fresh south westerly in direction.
Any lingering overnight rain or drizzle in the southeast will quickly clear on Sunday to leave a bright, fresh day with a mixture of cloud and sunny spells.
It will be predominantly dry but a few light showers may develop during the afternoon.