Thunderstorms have started to cause travel disruption across the county.
The Met Office had issued a yellow weather warning for parts of Kent and said it may lead to disruption due to flooding.
Thunder and lightning have already been seen and heard across Medway.
Southeastern has warned passengers of disruption to one of its services. Heavy rain has flooded the line in Lenham.
And hail and flash flooding has already been spotted in Maidstone.
Forecasters had predicted the storm would start at midday, warning homes and businesses could be damaged by floodwater, lightning strikes, hail or strong winds, and say fast-flowing or deep floodwater could pose a danger to life.
Kent Highways says where we do see the showers there could be 25-35mm of rain falling in just an hour, with as much as 50-60mm in two to three hours in isolated locations.
If flooding does occur there could be more delays or cancellations to train and bus services, with the additional risk of power cuts and loss of other services to some homes and businesses.
Spray and flooding could lead to difficult driving conditions on the county's roads.
A yellow warning for rain is also in place.
The weather warning comes after much of the south east basked under blue skies at the start of the week, with temperatures reaching 21C in parts of Kent yesterday.