The southwest monsoon is expected to reach Kerala during the next two to three days, marking a sluggish start to the seasonal rains that are the lifeline of India's agri-based economy.

Earlier, the India Meteorological Department (IMD) had forecast the onset over Kerala on Friday (May 27) with help from the remnants of Cyclone Asani, that struck the Bay of Bengal a fortnight ago. The forecast had a model error of four days.

However, the influence of the remnant weather systems, that lingered over the southern peninsula, petered out, dashing the forecast of early onset over Kerala and a swift progress towards the north, the IMD said.

As per the latest meteorological indications, westerly winds have strengthened in the lower levels over the south Arabian Sea and deepened. As per satellite imagery, there is an increase in cloudiness over Kerala coast and adjoining southeast Arabian Sea. Hence, conditions are becoming favourable for monsoon onset over Kerala during the next 2-3 days, the IMD said.

The weather office declares the onset of monsoon over Kerala if 60 per cent of 14 weather stations in Kerala and Lakshadweep receive 2.5 mm or more rainfall for two consecutive days, aided by favourable windfield and outgoing longwave radiation.

The IMD had declared the onset of monsoon over Andaman and Nicobar Islands on May 16.

The monsoon has now reached the latitude of Kerala. However, the distribution of rainfall in the state is still not proper for the declaration of the onset," Akshay Deoras, a monsoon researcher with Britain-based University of Reading, said on Twitter.

"Forecasts continue to suggest that the onset could happen sometime between 30 May and 2 June, and it will not be robust, he said.

The IMD has forecast widespread light/moderate rainfall with thunderstorm/lightning over Kerala and Lakshadweep and isolated to scattered rainfall over Andhra Pradesh, Telangana, Karnataka and Tamil Nadu, Puducherry and Karaikal during the next five days under the influence of westerly winds blowing from the Arabian Sea.

The weather office has forecast scattered light/moderate rainfall with isolated thunderstorms over Jammu and Kashmir and Himachal Pradesh during the next four days.

It also said isolated rainfall over Uttarakhand, north Punjab, north Haryana, Uttar Pradesh and East Rajasthan was likely during the next two to three days.

According to the IMD, most parts of northwest and central India are likely to experience a gradual increase in the maximum temperatures by two to three degrees Celsius over the next three days.