Karimganj experiences a Humid Subtropical climate, classified as 'Cwa' under the Köppen climate classification. The region is characterized by significant seasonal variations, particularly concerning precipitation.
Winters (December to February) are mild, dry, and highly pleasant, with average temperatures ranging from 10°C to 25°C (50°F to 77°F). This is generally considered the best time to visit the city. Summers (March to May) are warm and increasingly humid, with temperatures frequently reaching 30°C to 35°C (86°F to 95°F).
The monsoon season dominates the climate from June through September. Karimganj receives heavy rainfall during this period, often exceeding 2,500 mm annually, driven by the southwest monsoon winds. This intense rainfall leads to high humidity and frequently causes the Kushiyara and surrounding rivers to swell, leading to localized flooding. Natural disasters primarily consist of these seasonal floods and occasional cyclonic storms originating from the Bay of Bengal.