We have now entered the last leg of Monsoon. The average rainfall for the month of September is only 173.5 mm. This is far less than the rainiest months of July and August. September has the risk of large rainfall variability as the daily normal rainfall figures are very low.
Monsoon generally bids farewell from Delhi-NCR and other northern plains by the second week of September. Withdrawal is generally not attempted before September 1 and commences from extreme west Rajasthan. However, Monsoon remains active for the entire month over the Peninsular, East and Northeast India. Click here to know more about Southwest Monsoon.
Statistically, the month of September witnesses the emergence of several systems in the Bay of Bengal. The daily normal rainfall figures start dropping as Monsoon enters the last phase. In the beginning of the month, the daily average remains at 7 mm, drops to 6 mm by middle of the month and by the third week it dips to 5 mm.
The performance of Monsoon in August was poorer than July. The month ended with a rainfall deficiency of 23%. In the entire month of August, only seven days received normal or above normal rainfall than the daily average. This led to the high rainfall deficiency for the month.
September rains in Northeast India
During this month, Northeast India either receives very heavy showers or lies dormant. In case it rains heavily, the daily rainfall figure could rise by even three times. In 2014, heavy rains in Northeast during the last Monsoon month actually swayed the cumulative rainfall figure by a great extent. It brought down the rainfall deficiency figure from 17% at beginning of the month to 12% as the season ended.
Northeast India has the capability to push the overall rainfall figure. It can single handedly mitigate or reduce country wide rainfall deficiencies.
Given the fact this September began with heavy rainfall in the northeastern states, we could say that the month could perform better than July and August. However, the season might as well end with below normal rainfall.
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