The lowest temperature this winter was recorded in the city on Wednesday night — 14.4 degrees Celsius, 3 degrees Celsius below normal.
The drop in temperatures worsened air quality, which fell under the ‘poor’ category. The air quality index (AQI) on Wednesday was recorded at 268, with 267 predicted for Thursday.
The minimum temperature at Colaba, representative of south Mumbai, was close to the normal mark at 19.7 degrees Celsius.
The lowest minimum for the month of January was recorded on January 29, 2012 at 10 degrees Celsius and the all-time low for the month was recorded on January 22, 1962 at 7.4 degrees Celsius.
Officials from the weather bureau attributed the fall in temperatures to cold winds from the northern parts of the country, especially after snowfall in the Himalayan states. “The drop in minimum temperatures is due to cold air advection — the movement of cold winds from northern parts of the country during winter months. In Mumbai, humidity levels both at south Mumbai and the suburbs are also low, which is allowing the cool conditions to settle during the night and early hours of the day,” said Shubhangi Bhute, director, Regional Meteorological Centre, India Meteorological Department.
She said the current conditions are likely to continue on Thursday, but Friday onwards temperatures are likely to fall further. “Depending on whether there is more snowfall in the northern parts of the country, we expect both day and night temperatures to drop further over the city over the weekend,” said Bhute.
Day temperatures on the other hand, were 2 degrees Celsius above normal on Wednesday. While Santacruz — representative of the suburbs — recorded 32.5 degrees Celsius, 1.4 degree Celsius above normal, 33.4 degrees Celsius was recorded at Colaba, which was almost 3 degrees Celsius above normal.
Navi Mumbai breathed the most polluted air in the city on Wednesday with an AQI of 327 (very poor). Other areas in Mumbai such as Andheri, Bandra-Kurla Complex, Malad and Mazgaon, all recorded ‘very poor’ AQI levels. Worli recorded the cleanest air in Mumbai with a ‘moderate’ AQI of 181.
“The sea breeze, which is responsible for dispersing pollutants during the evening from Mumbai’s air, has been setting in an hour late. This, combined with low moisture, has resulted in ‘poor’ pollution levels,” said Bhute, adding that the current trend is likely to continue till the weekend.
Difference in day, night temperatures leading to cough, cold and viral fever: IMD
With a large difference between the day and night temperatures in Mumbai over the past few days, officials from the weather bureau said it could lead to health issues, especially respiratory ailments.
Weather factors such as a shift in wind patterns and humidity levels was playing a major role for the difference in temperatures, said officials. “During the day, the city has been observing north-easterly winds that are warm along with an increase in moisture levels. However, by the evening the wind patterns are shifting to northerly, which means cold winds along with a drop in humidity levels,” said Shubhangi Bhute, director, Regional Meteorological Centre, India Meteorological Department (IMD). “The temperature fluctuation can lead to cough, cold and fever. People need to take precautions to protect themselves.”
Moisture levels were low across the city on Wednesday. Colaba recorded 61% humidity while only 40% was recorded at Santacruz.