Bangladesh has a humid, warm climate influenced primarily by monsoon and partly by pre-monsoon and post-monsoon circulations and frequently experiences severe local storms and tornadoes. Average temperatures are 26.1⁰C, but can vary between 15⁰C and 34⁰C throughout the year. The warmest months coincide with the rainy season (March-September), while winter (December-February) receives less rainfall. Bangladesh is one of the wettest countries of the world, with most areas receiving at least 1500 mm and others receiving as much as 5800 mm of rainfall per year. Rainfall is driven by the Southwest monsoon, which originates over the Indian Ocean and carries warm, moist, and unstable air, beginning approximately during the first week of June and ending in the first week of October. Major climate drivers in Bangladesh include the Easterly Trade Winds, the Southwest monsoon, and the El Niño Southern Oscillation (ENSO).
- Observed data indicate that the temperature is generally increasing in the monsoon season (June-August).
- Average monsoon season maximum and minimum temperatures show an increasing trend annually at the rate of 0.05°C and 0.03°C, respectively.
- An increasing trend of about 1°C in May and 0.5°C in November during the 14-year period from 1985-1998 has been observed.
- Significant increasing trends in the cyclone frequency over the Bay of Bengal during November and May, which are the main months for cyclone activity in the Bay of Bengal, have been observed.
This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.