Clear sky and bright sunshine greeted Calcuttans for the fourth straight day on Tuesday with a drop in the moisture level.

On Monday, southwest monsoon retreated from Bengal. The minimum relative humidity — a measure of the humidity in the atmosphere during the driest part of the day — was around 50 per cent on Tuesday.

Exactly a week ago, when the city was in the midst of a relentless wet spell, the minimum relative humidity was around 75 per cent.

The humidity level will further drop in the coming days, said a Met official.

Apart from three to four rain-less days, a dip in the moisture content is considered as a pre-requisite to announcing the retreat of monsoon.

A reversal in the flow of winds is the most important marker. Cold and dry winds from the northwestern parts of India replace the moisture-laden winds from the Bay.

"Northerly and northwesterly winds are entering Bengal. But their bite will be more pronounced once the temperature drops significantly in places like Punjab, Delhi, Uttar Pradesh, Bihar and Jharkhand," said the official.

The maximum temperature on Tuesday was around 32 degrees and minimum around 24 degrees. Both were about normal for this time of the year. The day was hot but bearable. The evening was pleasant.

The forecast indicates dry weather for the state over the next few days.