The Met Office has issued a weather warning over heavy rain and thunderstorms over Brighton and Hove and the surrounding area.
The thunder started before the warning took effect at 10am today (Monday 12 August).
After a lull, more rain and thunder are expected this afternoon.
The official forecaster said: “Heavy showers and thunderstorms may cause some disruption.
“There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes or hail.
“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.
“There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost.”
The warning lasts until 7pm today.
According to one forecast, the downpours will be particularly heavy on Saturday morning (17 August), with well over an inch of rain expected.
This is more than half the monthly average of 2in for August in Brighton and Hove.