Delhi's has an extreme climate. It is very hot in summer (April - July) and cold in winter (December - January). The average temperature can vary from 25oC to 45oC during the summer and 22oC to 5oC during the winter.
In summer adequate precautions need to be taken, to avoid the intense heat, such as wearing light cotton clothing, wearing a hat or sunshade while going outdoors and drinking plenty of liquids. In winter, wearing warm or woolen clothing will protect you from the cold.