An amber warning - the Met Office's second most serious alert - was in place until 9pm, advising the public to be prepared to take action against the severe weather conditions.
Torrential rain on Wednesday saw flash flooding render many main routes, particularly in south and east Belfast, impassable and people were forced to take extreme measures to negotiate the city streets.
Even the Red Cross were called into action, attending the flooded homes of those facing particularly difficult circumstances - including one family with a young child suffering from a respiratory illness.
"Flooding is traumatic for any household but, for some families, it can have immediate health implications too," Red Cross volunteer Clive Hamilton said.
"We have been on standby with our specially adapted mobile home, which usually responds to households affected by serious house fires.
"It gives people who've had to leave their home somewhere safe and dry to sit until alternative accommodation is found."
Between 6pm and midnight, we had over 700 calls. At one stage, it was so bad that they were taking a call every 20 seconds.
Dale Ashford, Fire Service
Canoes and even surf boards were put into action, while some vehicles - and a PSNI Saracen - were left stranded with flood water reaching up to the windows.
While the emergency services were out in force, other 'good Samaritans' who emerged during the unprecedented downpours included one man who stripped to his underwear to push a car and its trapped occupants to safety.
Almost two inches of rain fell in just a few hours, leaving drainage systems struggling to cope, manhole covers being lifted, and homes worst affected flooded by significant levels of potentially contaminated water.
Northern Ireland Water said it has assisted with the initial cleanup of 158 properties across the region which suffered internal flooding related to sewage.
It said the cleanup has been completed in 75 cases and expects 35 more to be finished by Thursday evening - as the company remains on "high alert".
A statement added: "The clean up for the remaining properties will resume first thing in the morning.
"Overnight, staff remain on high alert and will respond to any further reports of flooding."
To report flooding in homes, the number to call is the Emergency Flooding Incident Line on 0300 2000 100.
To find out if you are eligible for a £1,000 emergency funding grant - available only subject to an inspection - the number to call is Belfast City Council's freephone flood helpline on 0800 707 6965.
Those affected by flooding outside of Belfast can also avail of the funding and should contact their own local council for assistance - contact details for each council in Northern Ireland are provided on the NI Direct website.
Staff can arrange to have your property assessed and will also be available to offer advice about clean-ups, sandbags, sewage pump-out services, and bulky waste collections.
"To make sure our officers can assess the damage accurately, please make sure that you do not dispose of any damaged items," a Belfast City Council spokesman said.
"You can apply for this financial fund and it won't affect your eligibility to claim against your house insurance, if you have it."
Anyone worried that flood water has come into contact with their electrics should contact NIE immediately on 08457 643 643.
Teams of metering technicians are on standby and we will be visiting customers affected by flooding to check NIE equipment and, where possible, restore electricity supplies.
With the potential for slow-moving torrential downpours to sweep parts of Northern Ireland into Thursday evening, the Public Health Agency is continuing to warn of the hidden dangers posed by flood waters.
Fast-flowing waters, missing manhole covers and contamination from sewage could all pose risks.
Environment Minister Alex Attwood has called for each council in Northern Ireland to gather an emergency response group to address the flooding.
"I spent a large part of last night in the emergency room in Belfast City Council monitoring the ongoing situation and doing what I could to assist," Mr Attwood said.
Northern Ireland Water has said staff will remain on high alert until the threat of flooding has passed.
Were you affected by the floods? Send your snaps to our Widespread Flooding gallery - where you can check out Surfer Guy and Underwear Man in rescue mode!
Affected Greater Belfast areas include:-
- Brookerstown Road, Lisburn - closed due to a landslide.
- Belsize Road at Milltown Estate - closed due to a landslide.
- Mullaghcarton Road, Lisburn - closed.