Met Eireann has issued a Status Yellow rain warning for Clare, Kerry and Limerick.
Prolonged heavy showers are expected, which may see thunder and local hail.
Spot flooding in the areas is likely.
The warning is valid until 6am on Friday.
A separate Status Yellow wind warning is also in place for Clare, West Cork, Kerry and Limerick.
Strong and very gusty west to northwest winds will bring difficult travelling conditions and possible wave overtopping to the areas.
The wind warning is in place from 11pm tonight through to 4am Friday.
Generally, it will become drier later tonight as showers become isolated and some mist and fog forms.
Temperatures will drop to as low as 6 degrees over night. It will be coldest in Ulster and Leinster where frost is possible.
Friday will bring plenty of sunshine and scattered showers, mainly in the west and northwest at first and moving further east in the afternoon.
Highest temperatures of 8 to 12 degrees are expected with light to moderate west to northwest winds, occasionally increasing fresh and gusty.
Friday night will be mostly dry and clear although isolated showers are possible near north-facing coasts. Mist and fog will form as winds ease light and variable.
Frost and fog will clear Saturday morning and it will be dry and sunny for a time. Rain will develop in the southwest around lunchtime and will extend across Munster in the afternoon and evening.
Other areas will stay dry but increasingly cloudy.
We will see highest temperatures of 7 to 11 degrees in a light to moderate easterly wind, freshening in the southwest.
Saturday night will be wet as rain moves northeast across the country, followed by showers. There will be lowest temperatures of 2 to 8 degrees, coldest early in the night in the north. It will become breezier as a moderate east to southeast wind develops.
On Sunday, rain and showers will continue in the morning and afternoon, clearing eastwards by the evening leaving largely dry conditions with just isolated showers.
Highest temperatures will reach 7 to 13 degrees, coolest in Ulster, with mostly moderate variable winds. However, a spell of strong winds is possible in the south.