HEAVY rain is expected tomorrow as the Met Office issue a yellow weather warning.

The warning comes into effect from 9pm tonight, Wednesday, September 4.

Scattered heavy showers are expected to merge into longer spells of heavy, perhaps even thundery, rain overnight and into Thursday, September 5.

Where heavy downpours occur, between 20 and 40 millimetres of rain is possible within an hour or two.

Over a longer period a few places could see more than 50 to 60 millimetres, possibly even as much as 80 to 100 millimetres if repeated batches of heavy rain affect the same locations.

But what can be expected?

• Spray and sudden flooding could lead to difficult driving conditions and some road closures

• There is a small chance that homes and businesses could be flooded, causing damage to some buildings

• There is a small chance of fast-flowing or deep floodwater

• Where flooding occurs, there is a chance of delays or cancellations to train and bus services