Heavy and persistent rain is forecast for Derry on Wednesday, according to the Met Office.
Light to moderate northerly winds are also forecast with a maximum temperature 10 °C.
Some brighter spells and showers are predicted for Thursday, these wintry over higher ground.
It's to be mainly dry and sunny on Friday, then bright with scattered wintry showers on Saturday and widespread frosts at night.
The Met Office has also issued severe weather warnings for heavy rain in parts of Scotland, England and Wales.
Met Éireann also issued severe weather warnings for heavy rain in Leinster and Munster for most of Wednesday.