Flooding has left parts of south and east Belfast under water.
Sheets of brown water are coursing down parts of the city with the arterial Ormeau Road particularly badly affected.
A police spokeswoman said: "Police are warning motorists of widespread flooding and traffic disruption in south and east Belfast. Police are urging motorists to exercise extreme caution when driving and only travel if necessary."
The Hillhall Road near Belfast is closed due to flooding. Motorists are advised to seek alternative routes. There is also bad flooding on the Lisburn Road and Castlereagh Road.
A Northern Ireland Fire & Rescue Service (NIFRS) spokesman said: "Since 18.30 this evening NIFRS has responded to numerous calls, many involving requests for further assistance from local crews to deal with flood water.
"While our resources are heavily committed we can assure the public that additional resources have been made available to support our operational response."
Nationalist SDLP Stormont assembly member Conall McDevitt claimed Northern Ireland Water (NIW) has failed in their commitment to support residents in the Finaghy area of Belfast.
"Although we have exceptionally rainy conditions tonight, the fact is that NI Water has failed in their commitment to support residents here with sandbags or to come up with an emergency response plan should heavy rain fall."
A Northern Ireland Electricity spokeswoman said approximately 1,000 homes in South Belfast experienced disruption to electricity supplies this evening. "NIE emergency crews responded immediately and are currently working to restore power to the area as quickly as possible," she added.
An NIW spokeswoman said its call centre has received 2,800 calls. The incidents involved localised flooding. She added areas affected included Lisburn, Dunmurry, Belfast and Bangor.