A study of urban heat island and its association with particulate matter during winter months over Delhi

► Daytime cool island forms over central parts of Delhi in November and December. ► Central parts of Delhi are cooler by a maximum of 4-6 °C during daytime and warmer by a maximum of 4-7 °C during night. ► Significant negative correlations exist between daytime surface temperatures and AOD levels. ► Land use parameters have significant correlations with surface temperatures. ► The day time cooling at the surface is accompanied by a warming at 850 hPa levels and above.