Southwest monsoon normally sets in over Kerala on June 1, with a standard deviation of about seven days. IMD has been issuing operational forecasts for the date of monsoon onset over Kerala from 2005 onwards. An indigenously developed state-of-the-art statistical model with a model error of ± 4 days is used for the purpose, according to an IMD statement.

Last year, the monsoon arrived in Kerala on June 8. The IMD had forecast the arrival on June 4 with a margin of ± 4 days.

In its latest bulletin, the IMD has forecast heatwave conditions over Northwest India from May 16 and in the eastern region from May 18. Concurrently, heavy rainfall, accompanied by thunderstorms, lightning, and gusty winds, is anticipated over the southern states until May 20.

IMD has forecast above average monsoon rainfall in 2024, which augurs well for the country’s agricultural sector which was hit by erratic weather last year.

The monsoon, which normally arrives in Kerala around June 1 and retreats in mid-September, is expected to total 106 per cent of the long-term average this year.

The monsoon plays a key role in the Indian economy as over 50 per cent of the country's farmland does not have any other source of irrigation. The monsoon rains are also crucial for recharging the country’s reservoirs and aquifers from which the water can be used later in the year to irrigate crops.

India has emerged as a key exporter of foodgrains but had to resort to curbing overseas shipments of sugar, rice, wheat and onions in order to increase domestic supplies and keep prices in check due to the erratic monsoon last year which hit farm production. A robust growth in the farm sector helps to keep inflation in check.

IMD defines average or normal rainfall as between 96 per cent and 104 per cent of a 50-year average of 87 cm (35 inches) for the June-Sept season.

Apart from supplying food, the farm sector also plays a key role in providing a demand for industrial goods such as two-wheelers, fridges and fast moving consumer goods. An increase in agricultural production and incomes, therefore, apart from contributing directly to GDP growth also leads to an increase in industrial growth.