The heatwave has ended for now but that is hardly a relief for Calcuttans as the maximum temperature is set to hover around 40 degrees Celsius for the next few days.

The city recorded a maximum of 39.6 degrees Celsius on Wednesday, four notches above normal. This was the first time since Sunday that the maximum temperature dropped below 40.

Heatwave is marked by a maximum temperature above 40 degrees Celsius and 4.5 degrees or more above normal.

Between Sunday and Tuesday, the maximum temperature was above 40 degrees Celsius, against the normal mark of 36 degrees.

Though the heatwave has subsided, the city continued to suffer hot and unpleasant weather. The weather department has warned that the spell would continue for at least the next few days.

"A heavy thunderstorm is needed for the city to come out of this hot and uncomfortable spell. The conditions are not yet favourable for the development of thunderclouds. We expect the maximum to hover around 40 for the next few days," said G.K. Das, scientist, India Meteorological Department, Calcutta.

The temperature can fall a little after Sunday but there is hardly any chance of rain. So the discomfort is likely to persist, a weather department official said.

In summer, there is usually a trough of low pressure or a cyclonic circulation in the vicinity of Calcutta or near the Chhotanagpur Plateau. Additionally, a high-pressure belt forms over the Bengal or Odisha coast.

"The phenomena lead to moisture incursion from the Bay, which results in the formation of thunderclouds to the west of Calcutta. These clouds bring thundershowers late in the afternoon or in the evening, bringing relief to the city," the weather expert said.

"But this year, both the high and low pressure zones are missing. That explains the prolonged hot and dry spell.... Both heat and humidity are needed for the formation of thundershowers. At the moment, there is heat but not enough humidity. Thus there is no squall or showers coming to Calcutta or the rest of south Bengal."

Airport restrooms

Twelve retiring rooms were inaugurated at Calcutta airport's new terminal for transit passengers. The rooms are on the mezzanine floor of the arrival area.