The Met Office has issued a ’yellow’ weather warning for London and South East England, valid between 10am and 11.59pm on Monday, July 12.
The threat of flooding means that some buildings, including crucial homes and businesses, could be damaged.
Travel disturbances may also be imminent – some train and bus services may be delayed or cancelled, and flooding could lead to difficult driving conditions.
The Met Office advises any unnecessary journeys could be delayed until the worst of the rainfall clears.
Road closures are also a probability, potentially isolating some communities.
Additionally, some homes and businesses may experience power cuts and loss of other services.
A Met Office spokesperson said "slow moving, heavy showers" will begin to cover the South East with "fast-flowing or deep floodwaters" a possibility.
More information can be found at metoffice.gov.uk