Delhi-NCR Weather Today: Capital sees dense fog in May — Here is why Delhiites experienced 3rd coldest morning of the month in 122 years

From a foggy morning to a sultry afternoon, Delhi's weather on Thursday summarised the atypical patterns of the last 15 days and perplexed the residents.

After a long spell of rain on Wednesday, the minimum temperature plummeted to 15.8 degrees Celsius on Thursday, making it the third coldest May morning since 1901 when the IMD started keeping weather records.

Dense fog smudged landmarks in the morning as visibility levels dropped to 100 metres around 5:30 am in Safdarjung, according to the weather office. Harsh sunshine and high humidity troubled the residents during the day. Humidity levels oscillated between 80 per cent and 100 per cent at most places in the city.

Delhi has been experiencing cloudy weather and sporadic rainfall for the last 15 days, which is rare during this time of the year. May has been historically the hottest month in Delhi, with a mean maximum temperature of 39.5 degrees Celsius.

Officials attribute this to the back-to-back western disturbances, weather systems that originate in the Mediterranean region and bring unseasonal rainfall to northwest India.

Residents shared videos and pictures on social media of fog blanketing the city's skyline.

"Fog on a May morning in Delhi. Never ever before have I experienced this in over 4 decades of living in this city. This is surreal!" a Twitter user said.

"Fog in Delhi on a summer morning! Same time last year, we were in a heat wave!" another person said.

Weather department officials said high moisture content in air, calm winds and a significant difference between daytime and nighttime temperatures create conditions favourable for formation of fog.

According to the IMD, 'very dense fog' is when visibility is between 0 and 50 metres, between 51 and 200 metres is 'dense', between 201 and 500 metres 'moderate', and between 501 and 1,000 metres 'shallow'.

The Safdarjung Observatory, Delhi's primary weather station, recorded 30 mm of rainfall in 24 hours ending at 8.30 am on Thursday.

It logged a maximum temperature of 30.6 degrees Celsius, nine notches below normal, on Wednesday and a minimum temperature of 15.8 degrees Celsius on Thursday, the third lowest in the month in 122 years.

The all-time low of 15.1 degrees Celsius was recorded on May 2, 1969. The city recorded a minimum temperature of 15.2 degrees Celsius on May 2, 1982.

Another spell of rain is likely to hit Delhi from Friday until Sunday under the influence of another western disturbance, IMD officials said. The maximum temperature is likely to remain below 35 degrees Celsius until May 8.

The Met office has predicted below-normal maximum temperatures and fewer heatwave days in northwest India in May.

Delhi recorded more than 20 mm of rainfall in April, the highest in the month since 2017.

The Safdarjung Observatory recorded the maximum temperature at least 10 degrees below normal on Sunday, Monday, and Tuesday due to intermittent rainfall and cloudy weather.

The maximum temperature settled at 28.7 degrees Celsius on Sunday and dropped to 26.2 degrees Celsius on Monday, making it the coolest first day of May ever since the IMD started keeping weather records. The city recorded a maximum of 28.3 degrees Celsius on Tuesday.