The Met Office has issued a second warning as the recent hot spell came to a dramatic end.
Highs of nearly 30C have been recorded in the region over the past two days.
But the warm weather was replaced with thunderstorms today, causing flooding across Merseyside.
LIVE: Updates on flooding as torrential rain batters Merseyside
Initially, a yellow weather warning was issued for Thursday afternoon.
But The Met Office has now warned of further thunderstorms in Merseyside tonight.
They said: "Heavy showers and thunderstorms are expected to continue affect the area through this evening before slow decaying towards midnight.
"Whilst many areas will miss the most intense storms, torrential downpours are likely in a few places.
"Where these occur, there is potential for 20 to 30 mm of rain in less than an hour and up to 40 mm in two hours.
"This will have the potential to generate surface water flooding, especially if it falls over an urban area."
The Met Office also extended the thunderstorm warning until 11pm tonight.
The forecasters said there is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds
Where flooding or lightning strikes occur, there is also a chance of delays and some cancellations to train and bus services.
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