Monsoon will arrive in Kerala on June 6, five days after its normal date of onset. The India Metorological Department (IMD) said on Wednesday the rain would arrive on the southern tip of Kerala around June 1 and retreat from Rajasthan by September. On Tuesday, Skymet had predicted Kerala monsoon from 4 June.

“This year, the statistical model forecast suggests that the monsoon onset over Kerala is likely to be slightly delayed,” the IMD said in a statement, adding that the southwest monsoon onset was likely to set over Kerala on 6 June with a model error margin of plus/minus four days.

June 1 is the normal onset date for monsoon over Kerala, which marks the official commencement of the rainy season in India and the monsoon gradually progresses northward.

On Tuesday, private weather forecaster Skymet had said Kerala monsoon was expected on 4 June.

In its forecast, Skymet had said monsoon would be “below normal” this time with a 93 per cent Long Period Average (LPA) and a 5 per cent error margin.

“Arrival of monsoon over Andaman and Nicobar Islands will be on May 22, with an error margin of plus/minus 2 days. Southwest Monsoon 2019 is likely to make onset over Kerala on June 4, with an error margin of plus/minus 2 days,” PTI quoted Skymet CEO Jatin Singh as saying on Tuesday.

“It seems that initial advancement of monsoon over peninsular India is going to be slow,” he added.

Kerala has been intermittently receiving pre-monsoon rain with low intensity.

The IMD claims its forecasts on the date of monsoon onset had always proved to be correct between 2005 and 2018, barring an exception of 2015.

According to the IMD, the conditions are becoming favourable for advance of southwest monsoon over the southern part of Andaman Sea, Nicobar Islands and adjoining southeast Bay of Bengal during May 18-19.

IMD forecast for Kerala monsoon in last 5 years (2014-18)

2014

Actual Onset Date: 6 June
Forecast Onset Date: 5 June

2015

Actual Onset Date: 5 June
Forecast Onset Date: 30 May

2016

Actual Onset Date: 8 June
Forecast Onset Date: 7 June

2017

Actual Onset Date: 30 May
Forecast Onset Date: 30 May

2018

Actual Onset Date: 29 May
Forecast Onset Date: 29 May