"The maximum temperature at Alipore recording station here was 40.5 degrees Celsius, higher by six degrees from normal", Regional Met director G C Debnath said.
"Heatwave conditions will prevail in the southern and western districts of West Bengal till tomorrow", Debnath said.
The maximum and minimum humidity were 88 degrees and 28 degrees, respectively.
Though heatwave conditions were also prevailing in North and South Dinajpur and Malda districts in north Bengal, there would be some respite from tomorrow night, he said.
Chief Minister Mamata Banerjee had on Monday asked school authorities to announce early summer holidays to protect students from the severe weather.
Most schools here and the southern and western districts are likely to close by the end of the week.