A few droplets that hardly qualify as rain fell for a minute on Sunday evening after one of the hottest afternoons of the season with the Celsius touching 39.1 degrees.

Other than those out in the open, most people in rain-starved Calcutta failed to notice the miserly 0.1mm of rainfall that weather experts said was the result of a thundercloud moving towards the city from Baripada in Odisha and losing its steam before reaching its destination.

The system dissipated by the time it knocked on Calcutta’s doors because the air over the city was bereft of any moisture that was needed to sustain a good shower, a Met expert said.

“The thunderstorm travelled along the Bay of Bengal coast drawing moisture from the sea. But it fizzled out on its way to Calcutta because of the dry air,” said Gokul Chandra Debnath, the director of the India Meteorological Department, Calcutta.

The Alipore weather office, which recorded 0.1mm rain, sounded the alert that the maximum temperature for the next two days would be oppressive since no rain-bearing condition has been observed near the city.

Poor moisture supply robbed the city of much-needed relief as the mercury shot up to 39.1 degrees Celsius, a miserable four notches above normal, making Sunday the hottest day this April and the third hottest of the summer.

Only end-March was hotter this season with the Celsius touching 39.3 (+5) on March 29 and 39.9 (+6) on March 30, when heat wave was declared for a day.

At 2.30pm on Sunday, the reading was 39 degrees Celsius but relative humidity was on the lower side at 31 per cent. Experts said the dry air kept the weather from getting sultry despite the high heat.

The discomfort index, which indicates the effect of heat and humidity on the human body, read 64.4 degrees Celsius — 10 degrees above the comfort level.

The weather flattered to deceive when sky turned overcast all of a sudden around 3.30pm and conditions looked ripe for a cooling Nor’wester. Though the squall did not materialise, the sky remained cloudy through the evening and light rain fell around 5.30pm.

A cool breeze and a few raindrops were what the city finally got. “I was about to call my driver to bring the car from the parking lot but decided to walk when it started to drizzle… it’s been a long while and so why not enjoy the rain,” said Neha Agarwal who had gone to Belle Vue Clinic to see a relative.

“The rain stopped before I reached the car. I rolled down the windows to enjoy the breeze,” said the Salt Lake resident.

Most cars had their headlights on by 5.30pm and tree branches swayed for a while. About 6pm, it rained for a couple of minutes in the Esplanade area and the temperature dropped sharply.

At Victoria Memorial, the wind and darkness before time prompted many to retreat to their homes, fearing heavy rainfall and traffic jams. A few umbrellas popped open but most people tried to enjoy the pitter-patter and even posed for photographs.

“I was carrying an umbrella in my bag and whipped it out as soon as I felt the first few drops of rain. I would have liked the drizzle to last a little longer,” said 28-year-old Piu Saha, out with friends at the musical fountain on the Maidan.

The brollies came in handy more in the afternoon when the sun in concert with the city’s dry air belted one Celsius scorcher after another until it reached a crescendo at a touch below 40.

According to experts, there needs to be sufficient heat and moisture for the formation of thunderclouds. “Even though the heat was there, the city is unlikely to get thunderstorms because humidity is missing. Squalls forming in neighbouring states are not likely to make it to the city because of the dry air,” an expert said.