Onam: Onam is a ten-day festival that usually falls in the months of August or September, and it marks the homecoming of the mythical King Mahabali. 

In Idukki, like the rest of Kerala, Onam is celebrated with great fervor and enthusiasm. People decorate their homes with beautiful floral rangolis, known as pookalams, and prepare traditional Onam dishes like sadya, a feast served on a banana leaf that consists of various vegetarian dishes. 

During the ten days of Onam, people in Idukki participate in various cultural events and competitions, including boat races, dance performances, and games like tug-of-war. The highlight of Onam in Idukki is the grand procession of decorated elephants, called the Onam parade, which is a sight to behold.Onam is a significant festival in Idukki and Kerala, and it is celebrated with great joy and enthusiasm by people of all ages and communities. 

Vishu: It is a popular festival celebrated Kerala. It is typically observed on the first day of the Malayalam month called Medam, which falls in April according to the Gregorian calendar. 

During Vishu, people in Idukki typically wake up early in the morning and view the "Vishukkani," which is an arrangement of auspicious items such as rice, fruits, flowers, and coins displayed in front of a mirror. It is believed that viewing the Vishukkani first thing in the morning brings good luck and prosperity for the rest of the year. 

After viewing the Vishukkani, people in Idukki usually visit temples to offer prayers and seek blessings. They also wear new clothes, prepare traditional delicacies such as "vishu kanji" (a rice porridge), and exchange gifts and greetings with friends and family. 

In addition to these traditional customs, Vishu in Idukki may also include cultural programs such as music and dance performances, as well as sports events and fairs. Overall, Vishu is a significant festival in Idukki that brings people together to celebrate the beginning of a new year with joy and enthusiasm. 

Christmas: Christmas is a popular celebration in Idukki and is celebrated with great enthusiasm and fervor. 

The majority of the population in Idukki is Christian, and Christmas holds a special place in their hearts. The celebrations begin with the Advent season, which starts four Sundays before Christmas Day. During this period, people attend church services, sing carols, and participate in various other activities. 

On Christmas Eve, people attend midnight mass, which is a significant event in Idukki. The churches are beautifully decorated with lights and Christmas trees, and people dress up in their best attire. After the mass, people exchange gifts and greetings with their loved ones and indulge in a feast that includes traditional Kerala delicacies like appam, stew, and biryani. 

Christmas Day is a public holiday in Idukki, and people spend the day with their families and friends. They visit each other's homes, exchange gifts, and enjoy delicious food. Many people also participate in community events like Christmas fairs, charity drives, and cultural programs. 

Munnar Flower Show: Munnar Flower Show is an annual event held in the town of Munnar, located in Idukki district. The event showcases a wide range of flowers and plants that are indigenous to the region and attracts visitors from all over the country. 

The Munnar Flower Show is organized by the Munnar Floriculture Society and features displays of a variety of flowers, including orchids, roses, marigolds, and dahlias. The event also includes competitions, workshops, and exhibitions, which provide a platform for local farmers and gardeners to showcase their produce. 

The flower show is usually held during the peak tourist season in Munnar, which is between December and February. The event attracts a large number of tourists and locals, who come to witness the beautiful floral displays and participate in the various activities. 

Apart from the flower show, Munnar is also known for its scenic beauty, tea plantations, and wildlife sanctuaries, making it a popular tourist destination in South India.