The prevailing weather is being influenced by a trough extending from north interior Karnataka to the Comorin area across south interior Karnataka, Kerala and Tamil Nadu at about 5.8 km above mean sea level, along with an offshore trough running from south Gujarat to north Kerala.

For Chennai, the weather office has forecast a partly cloudy sky with moderate rain, thunderstorms and lightning during the evening and night hours on August 3.

Across the State, heavy rain is likely at isolated places over the ghat areas of Coimbatore, the Nilgiris, Theni, Tiruvannamalai, Villupuram, and Cuddalore districts, besides Puducherry, on Monday. Thunderstorms accompanied by lightning and gusty winds reaching 40-50 kmph are also likely over several parts of Tamil Nadu.

Moderate rain is expected at a few places over the remaining Western Ghats districts, north coastal districts, the Delta region and Karaikal, while the rest of Tamil Nadu is likely to receive light to moderate rainfall.

Rainfall activity is expected to continue through the week, though with reduced intensity. From August 4 to 8, moderate rain is likely at isolated places over the Western Ghats, north coastal districts, Puducherry and Karaikal, while light rain is expected over the remaining parts of the State.

Meanwhile, the State witnessed scattered rainfall on Sunday. Upper Bhavani in the Nilgiris recorded the highest rainfall at 213 mm, followed by Chinnakalar (160 mm), Sholayar (120 mm), and Valparai (100 mm). Several parts of Ranipet, the Nilgiris and Coimbatore also received significant rainfall.

Maximum temperatures, which remained 2-4 degrees Celsius above normal at many places on Sunday, are likely to fall by 2-3 degrees Celsius over parts of south Tamil Nadu during the next two days.