The southwest monsoon has weakened over the Arabian Sea and the countrywide rainfall deficit is at 31% till June 6, the India Meteorological Department said on Tuesday.

The monsoon has not yet moved beyond southwest Karnataka and the northern West Bengal, according to the weather agency. The monsoon has further advanced over some parts of Tamil Nadu, Puducherry and Karaikal, it added.

The agency predicted that an intense spell of rain will continue over North East India, sub-Himalayan West Bengal and Sikkim over the next five days. It, however, predicted that heatwave will prevail in isolated pockets in northwestern, central and eastern India over the next three days.

On Monday, the maximum temperature remained above the 45-degree Celsius mark in several parts of Delhi. Najafgarh was the hottest part of the national Capital as the maximum temperature touched 46.4 degrees Celsius, five degrees above normal.

The Safdarjung Observatory, which provides representative data for Delhi, said that the maximum temperature in Delhi was 43.5 degrees Celsius.

On Monday, the IMD had issued an orange alert and warned of a severe heatwave in Delhi and other parts of northwestern and central India for the next three to four days. An orange alert signifies that the authorities should be prepared to take action.

For the plains, a heatwave is declared when the maximum temperature goes up to 40 degrees Celsius or more and is at least 4.5 degrees above normal. A severe heatwave is declared if the maximum temperature crosses the 47-degree Celsius mark.