A yellow weather warning is in place for parts of Northern Ireland today.
The Met Office says thunderstorms are expected to form in some areas, which may lead to power cuts.
The warning started from noon and is valid until 11.59pm tonight.
A spokesperson said: "A few places may see thunderstorms causing flooding and disruption.
"Flooding of homes and businesses could happen quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds.
"Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services.
"Spray and sudden flooding could lead to difficult driving conditions and some road closures. Some communities might become cut off if roads flood.
"Power cuts might occur and other services to some homes and businesses could be lost."
The Met Office forecast for tonight says "some late sunshine this evening then clear spells, although showers may linger into the early hours across the south. Low cloud, mist and patchy fog may develop overnight. Minimum temperature 9 °C".
