The southwest monsoon set in over Kerala on Thursday, three days later than its usual date of June 1. Last month, the India Meteorological Department (IMD) had forecast the onset of the monsoon on May 30.The onset of the monsoon marks the beginning of the four-month rainy season in India. The Met Department has predicted moderate to severe thunderstorms over many parts of northwest, central and east India and south Peninsular India during the next two to three days.Owing to a western disturbance, the department has predicted light to moderate rain with thunderstorms over east Rajasthan, Haryana, Chandigarh, Delhi, Punjab and west Uttar Pradesh on June 5 and 6. East Uttar Pradesh will receive rain on June 5.Last week’s heatwave abated after May 31 due to large-scale thunderstorm activity due to the western disturbance. From June 11 to 17, there is a low probability of heatwave conditions over parts of northwest India (Uttar Pradesh) and parts of east India (Bihar, Jharkhand, Odisha, Gangetic West Bengal and Chhattisgarh) and the adjoining central India (Madhya Pradesh).From March 1 to May 31, India received 131.3 mm of rainfall, 1 per cent more than the usual rain. “Conditions are likely to become favourable for further advance of the southwest monsoon into more parts of central Arabian Sea, parts of Maharashtra, entire Karnataka and Tamil Nadu, parts of Telangana, Andhra Pradesh, the entire south Bay of Bengal, parts of the north Bay of Bengal and the entire northeastern states during the remaining days of the week,” the Met Department said.