Vishu is astronomical New Year day festival held in the state of Kerala in South India. Similar festivals are celebrated in Punjab and Assam, in India, around the first day in the Hindu month of Medam (April - May). This occasion signifies the Sun's transit to the zodiac Mesha Mesha Raasi (first zodiac sign) as per Indian astrological calculations. Vishu is also considered as the harvest festival of Kerala and thus the importance of this day to all Malayalees. In Assam this day is called Bihu, in Punjab Baisakhi (originally Vaishakhi) and in TamilNadu Tamil Puthandu or Vishu punyakalam. The word "Vishu" in Sanskrit means "equal". Therefore Vishu is more probably denoting one of the equinox days.

Although Vishu (first of Medam) is the astronomical new year day of Kerala, the official Malayalam new year falls on the first month of Chingam (August - September).

The festival is marked with offerings to the divine called Vishukkani. The offerings consist of a ritual arrangement in the puja room of auspicious articles like raw rice, fresh linen, golden cucumber, betel leaves, arecanut, metal mirror, the yellow flowers konna (Cassia fistula), and a holy text and coins, in a bell metal vessel called uruli. A lighted bell metal lamp called nilavilakku is also placed alongside. This arrangement is completed the previous night. On the day of Vishu, the custom is to wake up at dawn and go to the puja room with the eyes closed so that the Vishukkani is the first sight of the new season. Since the occasion marks the beginning of Malayalam New Year, it is also considered auspicious to read verses from Hindu Holy book Ramayanam after seeing the "Vishukkani". It is also believed by some that the page of the Ramayanam to which you open up will have a bearing on your life in the coming year. Devotees also throng the well-known temples like Sabarimala Ayyappan Temple, Guruvayur Sree Krishna temple to have a "Vishukkani Kazhcha" on the early hours of "Vishu" day.

Kani Konna (Cassia fistula), Kerala's regional flower, is a popular vishukanni"Vishu" is celebrated with more fanfare and vigour in North Kerala as compared to other parts of Kerala. Bursting crackers is part and parcel of the celebration especially for children. Elders gift firecrackers to children and every child vie with each other to make a world of their own. The smell of the lingering smell of the fire crackers on a Vishu morning is a long cherished nostalgic memory of any Malayalee. The people wear new clothes (Puthukodi) for the occasion and the elders of the family distribute tokens of money, called Vishukkaineetam, to the children, servants and tenants. People carry on this custom believing that in this way, their children will be blessed with prosperity in the future.

Vishu is also a day of feasting, wherein the edibles consist of roughly equal proportions of salty, sweet, sour and bitter items. Feast items include Veppampoorasam (a bitter preparation of neem) and Mampazhapachadi (a sour mango soup).