The Met Office has issued a severe weather warning for parts of Co. Derry.
The warning was issued on Wednesday morning and is valid from 12pm through to 8pm.
Spray and flooding on roads could lead to difficult driving conditions and longer journey times. There is a lower likelihood of isolated property flooding.
"Rain will become more persistent and widespread across Northern Ireland this afternoon and into the early evening. 20-25 mm of rain may fall in some spots in less than six hours," said the Met Office's Chief Forecaster.