Muscovites splashed through flooded streets after more than 48 millimetres of rainfall hit the city, authorities said, nearly double the previous maximum recorded back in 1887.
"This is a new historical record for mid-August," the meteorological centre said in a statement.
"The last record of 25.2 millimetres of precipitation was recorded in 1887."
The downpour saw a tributary of the Moskva River break its banks in northeastern Moscow and flooded at least one station in the city's sprawling subway system.
Emergency services said they had rescued some 80 people trapped in their cars and a bus on a flooded street in southern Moscow.
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