The maximum temperature in Kolkata on Tuesday was 38.6 degrees Celsius, a notch down from the day before.
But the minimum relative humidity rose on Tuesday, making the weather feel worse.
The humidity was enough to cause discomfort but not enough to create thunderclouds, said Met officials.
Around 3pm on Tuesday, the website of AccuWeather, a US-based forecasting agency, showed a temperature of 35 degrees. But the RealFeel was around 45 degrees, thanks to the humidity.
The Celsius is likely to touch the 40-degree mark on Wednesday again, according to the Indian Meteorological Department forecast.
In several districts, the Celsius was over 40 degrees on Tuesday. Bankura was the hottest with a maximum temperature of 44.1 degrees Celsius.
“The Celsius in Kolkata is likely to stay around 40 degrees for at least a couple more days. After that, the Celsius might dip a little but rain is unlikely,” said a Met official.