India, Jan. 12 -- A cold wave continued to sweep the region on Monday as the mercury in Delhi plunged 4.2 degrees below normal to 3.2degC, even as the air quality remained "poor", and was expected to deteriorate to the "very poor" category during the day. Similar weather is likely until at least Wednesday.

On Sunday, the mercury went up to 18.8degC, a degree below normal, and 20.2degC on Saturday. Sunshine is expected on Monday, even as icy cold winds are likely to keep the maximum temperature between 18 and 20degC and 19 and 21degC on Tuesday.

Safdarjung, Delhi's representative weather observatory, recorded a minimum temperature of 3.2degC, Palam 3.3degC, and Lodhi Road 3degC on Monday.

The lowest minimum temperature recorded in Janua...