Ratnapura District was the most affected by the torrential rains accompanied by strong winds, which lashed several parts of the country.
The Meteorology Department said heavy rains were reported from the Galle District, the Sabaragamuwa and Central Provinces.
The residents of Kalutara, Agalawatta, Kelaniya, Galle, Matale, Bibila, Mawanella and Vavuniya were also affected by heavy rains and winds during the past 24 hours.
At least 316 people from 84 families in Ratnapura were affected while some 50 families at Seruwila in Trincomalee, Oddusudan and Welioya in Mullaitive were also known to have been adversely affected.
The Met Department said the highest rainfall of 197.5 mm was reported from Balapitiya.
The Disaster Management Centre (DMC) said residents living along the lower bank of Nilwala Ganga and Gin Ganga had been advised to be vigilant because the water levels rapidly rising to minor flood levels.
They said the water level in the Kelani Ganga and the Kalu Ganga which had risen yesterday were decreasing.
Meanwhile, the Met Department said rains could be expected in the Western, Sabaragamuwa, Sourthern, Central and North-Western Provinces tomorrow because the South-West Monsoonal conditions were breaking over the country.
“Heavy rain fall of more than 150 mm can be expected at some places. There may be temporary localized strong winds during thundershowers,” it said.(Ajithlal Shanthaudaya, Romesh Madushanka, Lal S. Kumara, S. Madawala)