The southwest monsoon is likely to hit the Kerala coast by June 5, the Indian Meteorological Department announced on Thursday.

As the onset date comes with an error margin of four days on either side, the monsoon’s entry into the mainland may happen anytime in the first week of June. The normal date for monsoon onset in Kerala is June 1.

“Monsoon is expected in the Andaman and Nicobar islands by May 20. Afterwards, it will be a little delayed,” Pune-based monsoon forecaster Shivanand Pai told Deccan Herald. The date is predicted based on a six-parameter statistical model.

The weather agency also said conditions have become favourable for advance of southwest monsoon over south Andaman sea and southeast Bay of Bengal in the next 48 hours. “The subsequent delay is a minor one,” said another IMD scientist.

Last month, the IMD forecast “below-normal” monsoon in 2014 as the expected precipitation is 95 per cent of the average rainfall. The forecast will be upgraded in June, taking into account the progress made in the march of monsoon over the landmass.

El Nino effect

The culprit behind the sub-normal forecast is El Nino — an unusual warming of the Pacific Ocean — which influences weather all over the world.

Even though there was 60 per cent probability of El Nino adversely affecting the monsoon, the El Nino conditions might become even more serious later as the depth of warm water is increasing, said a scientist. As most of India lacks irrigation, monsoon is a major hope for farmers, who rely on the rain for better farm yield. A sub-normal monsoon can reduce agriculture production.

In the last nine years, the onset of south west monsoon was most delayed in 2005 when it came on June 7 followed by 2012 when Kerala coast experienced the rain on June 5. Otherwise, monsoon came mostly in the last week of May.