Boishakh is the first month in the Bangla Calendar used in Bangladesh

Bangladesh

Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

 and parts of India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

.
Baisakh is also the first month in the Nepali calendar

Nepali calendar

The Nepali Calendar is a traditional solar calendar used in Nepal for both civil and religious purposes. The year begins in the month Baishakh; usually around 14 April....

 which uses the Bikram Sambat. It is the 2nd month in Hindu calendars following Shalivahana Shaka.

The name of the month is derived from the position of the Sun

Sun

The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 near the star Bishakha. The first day of Baishakh is celebrated as the Pôhela Boishakh

Pohela Baishakh

Bengali New Year or Poyela Boishakh is the first day of the Bengali calendar, celebrated in both Bangladesh and West Bengal, and in Bengali communities in Assam and Tripura...

 or Bangla New Year's Day. The day is observed with cultural programs, festivals and carnivals all around the country. The day of Pôhela Boishakh is also the beginning of all business activities in Bangladesh

Bangladesh

Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

 and neighboring Indian state of West Bengal

West Bengal

West Bengal is a state in the eastern region of India and is the nation's fourth-most populous. It is also the seventh-most populous sub-national entity in the world, with over 91 million inhabitants. A major agricultural producer, West Bengal is the sixth-largest contributor to India's GDP...

. The traders purchase new accounting books called 'Halkhata'. The accounting in the 'Halkhata' begins only after this day. The shops also offer sweets and other gifts to customers.

The month of Boishakh also marks the official start of Summer. The month is notorious for the afternoon storms called Kalboishakhis. The storms usually start with strong gusts from the north-western direction at the end of a hot day and cause widespread destruction.

Baishakh is the month when many of the seasonal fruits, especially mango

Mango

The mango is a fleshy stone fruit belonging to the genus Mangifera, consisting of numerous tropical fruiting trees in the flowering plant family Anacardiaceae. The mango is native to India from where it spread all over the world. It is also the most cultivated fruit of the tropical world. While...

 and jackfruit

Jackfruit

The jackfruit is a species of tree in the Artocarpus genus of the mulberry family . It is native to parts of Southern and Southeast Asia. It is the national fruit of Bangladesh, . The jackfruit tree is believed to be indigenous to the southwestern rain forests of India...

become available.