Soaring humidity under the impact of a storm brewing over the Bay of Bengal made the weather seem at least 10 degrees hotter in Calcutta than it was on Sunday.

The Alipore Met office on Sunday recorded a maximum temperature of 37.4 degrees Celsius, a couple of notches more than normal and marginally less than Saturday’s 37.5 degrees.

The RealFeel calculated by weather portal Accuweather around the same time was, however, 47 degrees Celsius — the season’s highest so far.

Saturday’s RealFeel was 45 degrees.

RealFeel, a measure of the effect of the weather on the human skin when one is outdoors, takes into account various parameters such as the temperature, humidity, angle of the sun and the wind speed.

Weather department officials blamed high humidity for the rise in the RealFeel.

A weather department official said a cyclonic storm that formed over the south-east Bay of Bengal on Sunday was feeding the city air with loads of moisture, making conditions uncomfortable.

“The same storm could trigger rain around Thursday, bringing some relief from the swelter,” the official said.

The minimum relative humidity, which shows the moisture content in the air during the hottest part of the day, read 56 per cent on Sunday. According to the Met department’s record, this was the highest minimum relative humidity over the past fortnight.

“Cyclonic storm Fani has formed over the south-east Bay of Bengal, 690km from Trincomalee in Sri Lanka. It is moving north slowly. Southwesterly winds are blowing across the entire eastern India because of the storm. The wind, coming from the direction of the sea, is pushing up the humidity level,” a senior Met department official said.

The cyclone is too far away from the city to trigger any rainfall right now. Meteorologists, however, expect cloud formation to start in Calcutta on Wednesday. Showers are likely on Thursday.

“The cyclonic storm is moving at 10kmph towards the Andhra Pradesh coast. It is expected to intensify into an extremely severe cyclonic storm by Wednesday. But it is likely to recurve in the north-north-east direction and stay on the sea for a few more days instead of making landfall,” the Met official said.

This movement is likely to bring the storm close enough to Bengal to influence its weather.

“It is, however, not clear at this stage whether the cyclone would recurve again and make landfall in India or keep going towards the Bangladesh or Myanmar coast. How much rain Calcutta gets and over how many days will depend on the last-leg movement of the storm,” the official said.

The heat that is tormenting Calcuttans now is being generated by two factors — the sun beating down through clear skies and the heatwave conditions in central India.

Pedestrian injured

A pedestrian was hit by a scooter on Bentinck Street on Saturday evening. The injured is being treated at a hospital. The rider has been arrested by the officers of Hare Street police station.