The Meteorology department said on Sunday that the minimum temperature, recorded just before sunrise, was 19 C as compared to 22.7 C a week earlier.
At Meenambakkam, the minimum temperature fell to 18.2C.
Reversal of winds from easterly to north-north westerly has been attributed as the reason.
“The drop in temperature is due to winds from the cold northern and northwestern parts of the country. The inland winds may persist until Tuesday night before wind direction changes again. When the easterly and north-easterly winds resume, the temperature will be back to normal,” said Mahesh Palawat of Skymet Weather.
The minimum temperature at Meenambakkam was nearly 1 degree C lower than the figure recorded at Nungambakkam.
Weathermen attributed this to the fact that Meenambakkam is 8km to 9km away from the sea, while Nungambakkam is just 4km from the coast.
The city generally experiences an average maximum and minimum temperature of 29.3C and 21.2C at Nungambakkam in January.
Partly cloudy skies have been forecast on Monday with little to no possibility of rainfall.
The Met office said that Monday’s maximum temperature is likely to be 29 degrees C and the day’s minimum 19 degrees C.
Last year, in November, the city had recorded its coldest day of the year when the maximum temperature fell by nearly five degrees below normal.
However, the coldest night of the year had been witnessed in January 2017 when the minimum temperature fell to 20 degrees C.