The India Meteorological Office today said conditions were favourable for the commencement of northeast monsoon rainfall in the southern region by Thursday as rains lashed many parts of Tamil Nadu.
''Conditions are favourable for the commencement of northeast monsoon rainfall over Tamil Nadu and Kerala and adjoining areas of south Andhra Pradesh and Karnataka during next 24 hours,'' the India Meteorological Department (IMD) said in a bulletin.
The southern parts of the country - Tamil Nadu, coastal Andhra Pradesh, Rayalaseema, Kerala and south interior Karnataka - receive about 30 per cent of their annual rainfall during the northeast monsoon season between October and December.
Tamil Nadu in particular gets about 48 per cent of its annual rainfall during this season.
The IMD has forecast ''most likely above normal'' rainfall during the northeast monsoon this year.
''The probability of above normal 2015 northeast monsoon season rainfall over south peninsula and over Tamil Nadu is 88 per cent and 90 per cent respectively,'' it said.
Rains lashed in many parts of the state, with Vallam (Thanjavur district) recording the highest of 9 cms.
According to the daily rainfall data, recorded till 8.30 am today, released by the Regional Meteorological Centre, Tambaram (Kancheepuram district) and Mettupalayam (Coimbatore district) received 7 cm each followed by Chembarambakkam (Tiruvallore) with 5 cm.