MUMBAI/ PUNE, Dec. 21 -- The Santacruz observatory registered a minimum temperature of 14.6degC in Mumbai on Saturday, which is 3.4 degrees below normal, according to the India Meteorological Department (IMD). It also declared that this was the coldest December morning yet. The Colaba observatory registered the minimum temperature at 20.1degC, 0.9degC below normal. Mumbai's overall Air Quality Index (AQI) at 4pm was 105, placing it in the moderate category, according to the Central Pollution Control Board (CPCB). Meanwhile, cold wave conditions deepened across Pune district, with Haveli recording the season's lowest minimum of 6.9degC. This was the first time this winter that temperatures in the district fell below 7degC. Pune city's minimum temperature was 8.1degC, the tenth instance this month when the mercury dipped to single digits. P3...