Skymet weather

Southwest Monsoon 2018 may make timely onset in Kerala

May 5, 2018 8:00 AM |

Northeast Monsoon to make delayed onset over South India

As the country gears up for Monsoon season, the hype around its arrival date has also started gaining momentum. The official date for the onset of this four-month long season is June 1, with onset five days before or after being termed as normal.

As per Skymet Weather, weather models are indicating that Monsoon 2018 is most likely to make timely onset over Kerala. Skymet Weather has predicted normal Monsoon 2018 to the tune of 100% (with an error margin of +/- 5%) of LPA (long period average) of 887 mm from June 1 to September 30.

Southwest Monsoon reaches Andaman and Nicobar Islands 4-5 days before reaching the Indian mainland of Kerala. However, lot of calculation are being done before the declaring the arrival of the most awaited season over the country.


According to weathermen, the Monsoon are not steady winds and are rather pulsating in nature. Onset of Monsoon is always subject to fulfillment of meteorological conditions which include rainfall records at 14 specified locations, the wind field both in terms of speed and depth and outgoing longwave radiation (OLR).

Although normal date of monsoon is June 1 but there has been early as well as delayed onset. However, arrival of Southwest Monsoon has been never attempted before May 10.

To be precise, there has been huge variation in the onset dates. In last 47 years i.e. since 1971, there has been only three occasions when Monsoon had made onset on June 1. These years were 1980, 2000 and 2013.

As per the records, the earliest arrival of Monsoon was on May 18, 2004, while the latest arrival was on June 18, 1972. Out of 47 years, there has been 20 years when Monsoon arrived on June 1 or before wherein in 10 years saw Monsoon reaching even before May 26.

Meanwhile, Monsoon arrive after June 1 rest 27 years on June 1 or after wherein in 9 years saw Monsoon reaching after June 5.

However, onset of Monsoon has no relation with the progress as well as performance of Monsoon. Earliest arrival of Monsoon on May 18 of 2004 gave below normal rains to the tune of 86%, resulting in drought. Meanwhile, the delayed arrival of Monsoon on June 13 in 1983 gave excess rainfall to the tune of 113%.

Skymet Weather will soon come out with the prediction for the onset date of Monsoon 2018 along with its progress.

Image Credit: India monsoons

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