Monsoon rains have been inadequate over Northeast India, this season. The last one week to ten days have gone literally dry and therefore, the rain deficit has increased over all the sub-divisions of Northeast India. Lack of precipitation has shot up the day temperatures. The entire region as such remains rather humid and therefore the combination of heat and humidity is deadly. Practically, it is sweltering all over and nearly causing heat wave conditions in the Assam Valley, with the only difference that mercury has not breached 40°C, and falls short of the heat wave criteria.
The persistent heat can be attributed to a series of monsoon systems over the Bay of Bengal, in the month of September. These systems have retained the valley easterlies for fairly long. Such scenarios do not favour any significant rains over Northeast India. Normally, southerly to southwesterly flow, which mostly follows after the monsoon systems move inland, has been missing. The mercury has shot up, just short of 40°C, at many places. Yesterday, the maximum temperatures at some locations were: Guwahati-39.3°C, Dibrugarh-39.5°C, Lakhimpur-39.6°C, Silchar-39.1°C and Tezpur-38.3°C. All these temperatures are 7°-8°C above the normal range. Humidity levels were in excess of 60% during afternoon hours. Most other places like Jorhat, Mazbat, Dhubri, Golaghat have also recorded temperature 5°-6°C above the normal. Extreme heat has led to closure of schools in Guwahati, for this week.
There is a relief likely around mid-week. Rain and thundershowers over various parts will better the comfort levels. There is a likelihood of the formation of a low-pressure area over Northwest Bay of Bengal, in the next 24 hours. The inland movement of the low pressure will change the wind pattern, this time. The valley easterly winds are going to be replaced with the southwesterly flow in the lower and middle levels. Fairly widespread rainfall is expected over Assam, Meghalaya and Arunachal Pradesh between the 25th and 27th of September. The north-south range of Nagaland, Manipur, Mizoram and Tripura will also receive moderate to heavy showers during this period. Mitigation of heat is likely over the entire Assam Valley. The day temperatures may slump to low 30’s, including at the state capital Dispur-Guwahati.