The Met Office has issued a yellow warning as heavy rain has raised fears of flash flooding in parts of Derry.
And even more heavy rain is to come.
The River Faughan in Drumahoe has already burst its banks along parts of the Fincairn Road.
According to the Met Office, a period of occasionally heavy rain is expected to develop during Monday night and then last through much of Tuesday morning. Rainfall totals of 15-25 mm can be expected widely, with as much as 40 mm over high ground.
Its website said: “The public should be aware of the risk of localised flooding and potential disruption to travel.”