It will turn very cold tonight, with temperatures falling between -4°C and -6°C.There will be a severe air and ground frost, so caution should be exercised on roads.
The warning is in place from 9pm this evening until 10am tomorrow morning.
The warning was issued for Munster, inland areas of Leinster, and Connacht, as well as counties Donegal, Monaghan and Cavan.
It will remain dry and clear but frost is expected to form overnight.More news: The ultra-slim Swift 7 is Acer's thinnest laptop ever
The orange warning, which includes most of Ireland, states temperatures could plummet to as low as -6 degrees Celsius.
"A mostly dry day will follow with sunny spells for a time, but cloud will gradually thicken from the south, with patchy drizzle developing near the south coast". It will be cold with an added wind chill from a brisk easterly wind with a maximum temperature of 7 °C.
"Winds light to moderate southeast in direction but fresh to strong and gusty along Atlantic coasts".