Bengaluru,  Heavy rains lashed many parts of coastal and south Karnataka, as the southwest monsoon intensified and advanced across the state, said the weather office on Monday.

"Heavy and widespread rains were reported in coastal and southern districts, while rainfall occurred at a few places in the northern districts of the state," said the India Meteorological Department (IMD) in a statement here.

With the monsoon being active due to favourable conditions, including strong surface winds and dark clouds, 9 cm rainfall was recorded during the day at Panambur and Kota in Udupi district, Bhagamandala in Kodagu district and Agumbe in Shivammoga district.

As much as 8 cm of rainfall was measured at Mangaluru and 7 cm at Subramanya in Dakshina Kannda district, Gokarana, and Mani in Uttara Kannada district, Karkala in Udupi district and at Aurad in Bidar district.

The met office has issued red alert in Dakshina Kannada, Udupi, and Uttara Kannada districts along the coast, forecasting heavy to very heavy rains over the next 24 hours, with thunderstorms and lightning.

"Orange alert has been sounded in Kodagu, Hassan, Chikkamagaluru, Shivammoga, Belagavi, Dharwad and Haveri districts where widespread and heavy rains are likely to occur on Tuesday," said the IMD.

Fishermen in the state's coastal area have been advised not to venture into the Arabian Sea due to strong surface winds up to 55 kmph on Tuesday.

During the fortnight since June 1, the southern state received 310 mm rainfall, which is 1 per cent above average (306 mm), with 70 mm, which is 45 per cent above average, recorded in the northern region, and 74.4 mm, which is 26 per cent above average in the southern.

"On Monday, 96 mm rainfall was recorded across the state, which is 21 per cent above normal. Coastal area recorded 49 mm, which is 46 per cent above normal," added the statement.