Severe weather warnings have been issued for heavy showers and thunderstorms on Friday and Saturday.
Met Office alerts for Northern Ireland began at 11:00 BST and will stay in place until 21:00 BST on both days.
The agency advises people to expect disruption as homes and businesses could be affected by flood water.
It also says to expect disruption to public transport where flooding and lightning strikes occur.
According to the fire and rescue service, half of the Meadowlane shopping centre in Magherafelt in County Londonderry has been shut down due to flooding.
The fire service were at the scene helping staff to clear the three to four inches of water.
On Friday night police confirmed that localised flooding around Magherafelt town centre had started to ease.
The Met Office advises:
- There is a small chance homes and businesses could be flooded quickly
- There is a small chance of fast flowing or deep floodwater causing danger to life
- There is a slight chance that power cuts could occur and that some service
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Due to the nature of showers it is impossible to predict where they will hit, with many places avoiding them altogether.
However, some might get more than their fair share.
NI Direct has issued advice and information ahead of the heavy downpours.
A spokesperson for the Department of Infrastructure said it was aware of the yellow warnings and statutory bodies had been in contact to "prepare for any impacts from weather over the next few days".
"We will continue to closely monitor the weather and staff will be placed on standby to respond to any impacts as needed," the spokesperson said.
It recommends making a note of emergency contact numbers and government agencies, and also provides advice on how to prepare for a flood.
Met Éireann, the weather service in the Republic of Ireland, has also issued a warning for Ireland.
It says as much as 50mm of rain could fall in a short amount of time, leading to spot flooding.