An on-going cyclonic circulation in the Arabian Sea could slow down the progress of monsoon.

A delay in the arrival of monsoon has pushed the country's rainfall deficiency in the first nine days of June to 45 per cent, the India Meteorological Department said today.

Monsoon made an onset over Kerala on June 8, a week after its normal arrival date. This has also delayed its arrival in different parts of the country.

The country received only 17.7 millimetres of rainfall as against the normal precipitation of 32.4 millimetres, which comes to around 45 per cent, it said.

The rainfall deficiency in June could be higher due to the sluggish pace of the monsoon and a weak El-Nino, a phenomenon associated with heating of Pacific waters.

An on-going cyclonic circulation in the Arabian Sea could slow down the progress of monsoon over the next few days, it said.

"A low pressure area has formed over southeast Arabian Sea and adjoining Lakshadweep area and east central Arabian Sea. It is very likely to concentrate into a depression during the next 48 hours over southeast and adjoining east central Arabian Sea. It is very likely to move north-northwestwards and intensify further into a cyclonic storm subsequently," the IMD data said.

Of the four meteorological divisions of the country, the deficiency was 66 per cent --- the highest in the country --- in central India that covers the states of Maharashtra, Madhya Pradesh, Gujarat, Goa, Odisha and Chhattisgarh.

Gujarat and Kutch and Saurashtra sub-divisions of central India have clocked a deficiency of 100 per cent, it said.

The situation is particularly grim in Maharashtra, especially in Vidarbha and drought-hit Marathwada where the deficiency touched 70 per cent and 50 per cent, respectively. To add to the woes, the reservoir levels in these areas have hit low levels.

The monsoon deficiency in east and northeast India division comprising Jharkhand, Bihar, West Bengal and all the northeastern states was 49 per cent, the IMD said.

Deficiency in the south peninsula which covers all the south Indian states was 29 per cent, the least in the country. Monsoon has covered some parts of Kerala and Tamil Nadu.

Rainfall deficiency in northwest India was 32 per cent.

On the other hand, mercury continues to soar in the north Indian plains and central India.

Heat wave to severe heat wave conditions are very likely to prevail over Rajasthan, Madhya Pradesh, Vidarbha, southern parts of Haryana and Uttar Pradesh during the next two days, it added.