New Delhi, Jan 18 (IANS): Delhi-NCR on Tuesday recorded its sixth consecutive cold day with isolated pockets recording a severe cold day, India Meteorological Department (IMD) data showed.

The maximum temperatures dropped to a low of 12.8 and 13.1 degrees Celsius -- almost 7 notches below normal -- at Jafarpur and Narela, respectively.

While Safdarjung recorded a maximum temperature of 15.4 degrees Celsius, Palam 13.8 degrees Celsius, Lodhi Road's temperature dipped five degrees below normal at 16.1 degrees Celsius.

Delhi has been reeling under a cold day spell for six consecutive days, starting January 13.

There was a layer of moderate fog/low cloud during the day over Delhi NCR, the weather department has said, and this has prevented sunlight from reaching the surface.

IMD denotes cold day with yellow alert when there is a departure of 4.5 degrees or more in the maximum temperature. Similarly, it uses orange alert for severe cold when there is a departure of 6.5 degrees Celsius or more.

District-wise warnings for severe weather such as thunderstorms, heavy rainfall, for six consecutive days, are provided by the IMD in colour-coded form for the public to easily understand the weather conditions in a particular area. The different colour codes signify the intensity of the weather conditions in that specific area.

According to the Standard Operating Procedure of the Weather Forecasting and Warning Services provided by the IMD, "colour codes are used in weather warnings for bringing out the severity of the weather phenomena expected".