Five other people are still missing after parts of the capital Riyadh and the northeastern city of Arar were inundated, authority spokesman Colonel Abdullah al-Harithi told.
The storms that have accompanied the downpours have brought down power lines, sparking outages in parts of north Riyadh.
Schools and universities in the capital have been closed since Sunday.
Flooding of underpasses on major thoroughfares has sparked traffic chaos for Riyadh’s more than five million residents.
Saudi Arabia normally experiences such low rainfall that religious leaders often organise special prayers for rain.
But in May last year, around 20 people were killed in flooding sparked by the kingdom’s heaviest rainfall in 25 years.