The India Meteorological Department (IMD) announced on Tuesday that the onset of monsoon over Kerala is likely to be delayed by four days, with a model error of ± 4 days, and is expected to occur on June 4. This is slightly later than the usual date of onset of June 1, which is the beginning of the four-month monsoon season.
IMD said that in the past five years, only once has the onset happened on June 1. On two occasions, in 2018 and 2022, it happened a couple of days earlier, on May 29, while in 2019 and 2021, the onset happened a few days later. The onset of monsoon is just a marker for the beginning of the rainfall season and has no bearing on the amount of rainfall that happens during the season.
The IMD statement further stated that the six predictors used in the models for the onset of monsoon are Minimum Temperatures over Northwest India, Pre-monsoon rainfall peak over south Peninsula, Outgoing Long wave Radiation (OLR) over south China Sea, Lower tropospheric zonal wind over Southeast Indian Ocean, Mean sea level pressure over Subtropical NW Pacific Ocean, and Upper tropospheric zonal wind over North East Indian Ocean.
The IMD also mentioned that last year, the onset of monsoon over Kerala occurred on May 29, two days ahead of their predicted date and that the operational forecasts of the date of monsoon onset over Kerala during the past 18 years (2005-2022) were correct except in 2015.
Additionally, duststorms and dust-raising winds are very likely in isolated pockets over Haryana and Delhi, West Uttar Pradesh and Rajasthan during the next three days and over Madhya Pradesh and Vidarbha region during the next two days. Heatwave conditions in the first half of May were less severe due to Western disturbances that affected parts of northwest India. The temperature is expected to be up to 40°C in the next seven days.
Light to moderate widespread rainfall activity is expected over northeast India during the next five days, with heavy rainfall very likely at isolated places over Arunachal Pradesh on 16th, 19th & 20th; over Assam & Meghalaya and Manipur, Mizoram & Tripura during 16th to 20th May.