Weather Update: As several states across India continue to reel under scorching hot weather conditions and face the impact of heatwaves, the India Meteorological Department said on Tuesday that heatwave to severe heatwave conditions are likely to continue over East India till May 2 and will gradually begin to diminish thereafter. The IMD has also predicted that heatwave conditions will likely continue over south Peninsular India during the next 5 days.


Several states across India are prone to the severe impact of heatwaves. The Core Heatwave Zone (CHZ) spanning central, north, and peninsular India between Gujarat and West Bengal is majorly affected by heatwave conditions every year, during the summer season March to June, and quite often in July, as reported by the Indian Express.


The most heatwave-prone states or regions are Rajasthan, Punjab, Haryana, Chandigarh, Delhi, West Madhya Pradesh, Uttar Pradesh, Chhattisgarh, Odisha, Vidarbha in Maharashtra, parts of Gangetic West Bengal, coastal Andhra Pradesh, and Telangana.


In its latest update, however, the weather office also stated that heavy rainfall, accompanied by thunderstorms and gusty winds, will likely continue over northeast India during the next 3–4 days. In the last few days, the IMD has been issuing alerts and warnings pertaining to the heatwave conditions and rising temperatures across several states in the country  


On Monday, the weather office said that heatwave to severe heatwave conditions prevailed in most parts of Gangetic West Bengal, in a few parts of Saurashtra and Kutch, Bihar, Sub-Himalayan West Bengal, and Odisha, and in isolated pockets of Jharkhand, Kerala, Konkan, and Rayalaseema.


According to the IMD, dry weather is very likely to prevail in Bengaluru from April 30 to May 5. The city is also likely to see a maximum temperature of around 37 degrees Celsius over the next 48 hours, as reported by the Hindustan Times.


Why April Has Been Unusually Hot ?


The IMD has said that April has been unusually hot, as either a small pocket or a large geographical area in the country has witnessed heatwave conditions in the first 26 days. On one hand, the southern peninsular and southeastern coast areas have seen the worst effect, while on the other hand, the northern plains are yet to experience heatwave conditions this season.


According to the director general of the IMD Mrutyunjay Mohapatra, 2024 is a year that began in an El Niño state. It is a weather pattern, that refers to an abnormal warming of surface waters in the equatorial Pacific Ocean, leading to extreme heat in several parts of the world and the ocean, as reported by The Indian Express. It developed in June 2023, and generally, the years that begin in an El Niño state, experience extreme temperatures, harsh, multiple, and extended heatwave spells, and a lack of pre-monsoon rainfall. 


Another reason for the unusual heat this month, according to the weather office, is the persistent presence of anticyclone systems over southern peninsular and southeastern coastal areas, which is also partly responsible for such a hot April. These high-pressure systems, which exist at an altitude of about 3 km and extend between 1,000 and 2,000 km in length, push the air underneath them towards the Earth in a process called air subsidence. As a result, the forcefully sunk air generates more heat on the surface closer to the earth.


Orange Alert In Kerala


The IMD has issued an orange alert for the Palakkad district in Kerala amid heatwave conditions across the state, news agency ANI reported on Tuesday. Heatwave conditions are likely to continue at a few places in the Palakkad district from April 30 to May 4.


According to the IMD, maximum temperatures are predicted to hover around 41 degrees in the Palakkad district, around 40 degrees in the Thrissur district, around 39 degrees in Kollam and Kozhikode districts, around 38 degrees in Alappuzha, Kottayam, Pathanamthitta, and Kannur districts, and around 37 degrees in Thiruvananthapuram, Ernakulam, Kasaragod, and Malappuram districts (3 to 5 degrees above normal) during April 30 to May 4, ANI reported.


The weather office further stated that hot and humid weather is very likely over these districts except in hilly areas from April 30 to May 4 due to high temperatures and humidity. As per the IMD, heatwave conditions are likely to prevail at one or two places in Alappuzha, Thrissur, and Kozhikode districts from April 30 to May 4. Warm night conditions are very likely to prevail at one or two places in the Alappuzha district on April 30, the IMD said.


Above-Normal Monsoon Rainfall Likely In South Asia


The South Asian Climate Outlook Forum said on Tuesday that above-normal rainfall is expected during the 2024 southwest monsoon season over most parts of south Asia, as reported by news agency PTI. The forecast follows the prediction of above-normal rain in the monsoon season in India on the back of favourable La Nina conditions, expected to set in by August–September.


"Above normal rainfall is most likely during the 2024 southwest monsoon season (June-September) over most parts of south Asia, except some areas over northern, eastern, and northeastern parts of the region, where below-normal rainfall is most likely," the South Asian Climate Outlook Forum (SASCOF) said, as quoted by PTI.


Above-normal maximum and minimum temperatures are predicted over most parts of South Asia during the season, except a few areas in the southeastern part of the region where normal temperatures are most likely.


Rise In Temperature Scorches Queen Of Hills In TN


Udhagamandalam, known as the Queen of Hills in Tamil Nadu, does not seem to get any respite this summer as a spike in temperature has left the sequestered hill station scorched. The district saw its highest-ever temperature of 29 degrees Celsius on April 29, and this was 5.4 degrees above the average temperature for Udhagamandalam, said Additional Director General, Regional Meteorological Centre (RMC), Chennai, S. Balachandran. The previous all-time high temperature of 28.5 degrees Celsius was recorded on April 29, 1986.


The RMC has issued a warning about heatwave conditions at isolated pockets over north interior Tamil Nadu and a yellow alert for heatwave conditions until May 3. The meteorological department uses four colour codes – green (no action needed), yellow (watch and stay updated), orange (be prepared) and red (take action) – for weather warning.


When Does IMD Declares A Heatwave ?


The weather office declares a heatwave after the normal maximum temperature recorded over at least two localities in the plains breaches the mark of 40 degrees Celsius or exceeds 4.5 degrees Celsius from normal. In hilly areas and coastal areas, a heatwave is declared when temperatures cross 30 degrees Celsius and 37 degrees Celsius, respectively. A severe heatwave is declared if the temperature departure exceeds 6 degrees Celsius from normal.