Bangladesh is called the land of six seasons. It has a temperate climate because of its physical location.
Though the climate of Bangladesh is mainly sub-tropical monsoon, ie warm and humid; Bangla calendar year is traditionally divided into six seasons: Grisma (summer), Barsa (rainy), Sarat (autumn), Hemanta (late autumn), Shhit (winter) and Basanta (spring).
Each season comprises two months, but some seasons flow into other seasons, while others are short.
Actually, Bangladesh has three distinct seasons: the pre-monsoon hot season from March through May, rainy monsoon season which lasts from June through October, and a cool dry winter season from November through February. However, March may also be considered as the spring season, and the period from mid-October through mid-November may be called the autumn. Traditionally spreads over Asadh and Shraban (mid-June to mid-August).
However, the rainy season may start from the end of Baishakh and last up to the beginning of Kartik (mid-May to late-October). During the rainy season, the southwest monsoon winds bring plenty of rainfall (70 to 85 percent of the annual total) and occasionally lasting for days without end without any respite. Most of the floodplains of the country remain inundated during this period. Depending upon the local elevation, the depth and duration of barsha varies in different parts of Bangladesh.
For instance, in low lying parts like haors , beels , jheels of Sylhet, Netrokona, Kishoreganj, Gopalganj and Pabna districts inundation lasts for the longest period (more than six months). In other places, like the central parts of Bangladesh, it lasts for about 3 to 4 months. In the rural areas, boat navigation becomes a common mode of transport during this season.
Plants, half-dead with the summer heat, receive a new lease of life under cool rains and Bangladesh becomes green. Farmers are busy for harvesting jute , in the flood free areas and/or shallowly flooded (0 to 30 cm depth) areas for preparing paddy seedbeds.
Barsha is also important for the fishing community of Bangladesh. hilsa fish is available in plenty during this season.
The inundated floodplains become a large habitat for a wide variety of aquatic flora and fauna. At this time plenty of edible herbs grow everywhere, as does the national flower lotus. This is the season for keya, kadam, kamini, jui, gandharaj and other fragrant flowers, as well as fruits like guava, pineapple, and pomelo.