Madurai is hot year-round, but the best time to visit is October to March when temperatures are more bearable. The monsoon peaks in October-November. The city has one of the richest festival calendars in Tamil Nadu, and timing a visit around one of the major events is well worth the effort.
Jallikattu (bull-taming) takes place in villages near Madurai during Pongal in January. Young men compete to hold on to the hump of a running bull. The festival is controversial — it was banned and then reinstated after mass protests — but if you're in the area during Pongal, the village events at Alanganallur and Palamedu are extraordinary spectacles.
Chithirai Festival at the Meenakshi Amman Temple in April is Madurai's biggest religious event, drawing over a million pilgrims over ten days. The celestial marriage of Meenakshi and Sundareswarar is celebrated with massive processions.
Floating Festival (Teppam) at the Vandiyur Mariamman Teppakulam tank takes place in January-February (Thai month). Illuminated floats carrying the temple deities are taken in procession around the vast tank by night — one of the more beautiful temple festivals in south India.