Heavy rainfall pushed the Iraqi government to announce a day off on Wednesday in Baghdad.
Iraq's southern and central regions saw hours of torrential rains on Tuesday with experts describing it as the heaviest in 30 years.
The streets in many of Baghdad's districts, particularly in the central part, were flooded, forcing hundreds of vehicles to stop in night's cold weather.
In southern city of Baquba the heavy rain destroyed a house, killing all four people inside.
Officials said the four were siblings living in a shoddily-built house.