Flash floods are likely in the northeastern and south eastern districts during this month due to 'unusual rainfall', the Meteorological Department says.

The rainfall may be 10 to 15 percent above average.

The monsoon may spread all over the country by the 10th of the month and frequency of rain may be two to three times higher than normal, the Met office said.

The monsoon winds have already reached the Bay of Bengal and the country experienced heavy pre-monsoon showers.

The rainfall was above average in the past three months also. It was

49 per cent above average in March, 36 per cent in April and 22.4 per cent above average till mid-May.

An expert from the Flood Forecasting and Warning Centre said there is possibility of flooding next month because of above average rainfall in the past few months. But it will be of medium intensity, he said seeking anonymity.

Some meteorologists however compared the present situation with that of 1998 when there was serious flooding preceded by above normal rainfall.

But everything will depend on the amount of rainfall during the monsoon and in the upstream of the country's major rivers like Ganges,

Brahmaputra and Meghna, they said.

The long-range forecast said there is possibility of one or two seasonal depressions over the Bay during this month, which may trigger heavy rains.