With the monsoon’s arrival just around the corner, several states on Friday saw maximum temperatures dip below the 40-degree Celsius mark and braced for a wet spell, even as the IMD indicated a below-normal southwest monsoon rainfall over India in the upcoming season.The national capital wore a cover of clouds as it recorded a sharp fall in temperatures, with the lowest maximum registered over the past 21 days. The weather forecast for several northern states, including Punjab, Haryana, Himachal Pradesh, Uttar Pradesh and Uttarakhand, pointed to likelihood of rain and thunderstorms.Intense heat refused to ebb in Rajasthan, with mercury settling in the mid-forties. However, the weather department said thunderstorm and rain activity was expected to increase from Friday in the state.The IMD said many rain-fed agricultural regions across the country are expected to receive deficient rainfall.The IMD has also forecast above-normal heatwave days in June over many parts of Uttar Pradesh, Haryana, Punjab, Bihar, Odisha, Chhattisgarh, Gujarat and Andhra Pradesh, along with isolated regions of Maharashtra, Telangana, Himachal Pradesh and Tamil Nadu. However, below-normal heatwave days are likely over Rajasthan and Jharkhand.Climate models indicate the development of El Niño conditions during the southwest monsoon. El Niño conditions typically suppress and disrupt the southwest monsoon, leading to below-normal rainfall and raising the probability of drought.At present, the southwest monsoon has advanced into parts of the Andaman and Nicobar Islands since May 16. As of May 28, it had covered parts of the south Arabian Sea, Lakshadweep area, south Bay of Bengal, east-central Bay of Bengal, the entire Andaman and Nicobar Islands and the Andaman Sea.The IMD said El Niño conditions were currently weak, but were expected to strengthen in the coming months.“During June to September, below-normal seasonal rainfall is most likely over most parts of the country, except some areas over North-West and North-East India, eastern parts of the south peninsula, adjoining areas of east-central India and isolated pockets of east India, where normal to above-normal rainfall is likely,” the IMD said.Heatwave: NGT seeks action plan from CentreAs parts of the country sweltered under an “extreme heatwave crisis”, the National Green Tribunal (NGT) on Friday initiated suo motu proceedings on the issue and sought detailed climate adaptation strategies from the Centre and several state governments. The tribunal observed that extreme heat was not only affecting public health, but also having a widespread impact on agriculture, water resources, labour productivity, wildlife and the economy.IMD Director General Mrutyunjay Mohapatra said, “The southwest monsoon seasonal rainfall over the Monsoon Core Zone (MCZ), consisting of most of the rain-fed agriculture areas in the country, is most likely to be below normal.”“The maximum temperatures will be above normal except over some parts of central, North-West and east India, where normal to below-normal maximum temperatures are very likely. Above-normal monthly minimum temperatures are likely across most parts of the country, except some parts of North-West, central and adjoining south peninsular India, where normal to below-normal minimum temperatures are very likely,” the IMD said.The weather office warned that below-normal rainfall could create challenges for agriculture, water availability, hydropower generation and ecosystem sustainability, while increasing the risks of drought, heat stress and pressure on drinking water resources.“To minimise these impacts, strategies can include efficient water resource management, promotion of water conservation practices, contingency planning for agriculture, strengthening drought monitoring and use of IMD’s early warning services and enhancing preparedness measures in sectors particularly vulnerable to rainfall deficits,” the IMD added.India received 121.7 mm of rainfall between March 1 and May 27 this year.