Severe Tropical Storm Chalane was the first of three consecutive tropical cyclones that struck Mozambique in the 2020-21 South-West Indian Ocean cyclone season. As the fourth tropical depression, third named storm, and second severe tropical storm of the season, Chalane developed out of a zone of disturbed weather which was first monitored RSMC La Réunion on 19 December. Despite conditions slowly becoming unfavorable, the system formed into a tropical depression on 23 December due to the presence of a Kelvin wave and an equatorial Rossby wave, as well as warm sea surface temperatures. The depression soon strengthened into Tropical Storm Chalane on the following day. Chalane made landfall on Madagascar on 26 December and weakened, before emerging into the Mozambique Channel a couple days later. Subsequently, Chalane restrengthened, before making landfall on Mozambique on 30 December. The system weakened as it moved inland, degenerating into a remnant low later that day. However, Chalane's remnants continued moving westward for another several days, emerging into the South Atlantic on 3 January, before dissipating later that day.

The 2020–21 South-West Indian Ocean cyclone season was an above-average season which produced 12 named storms, with 7 strengthening into tropical cyclones. The season started with the formation of Cyclone Alicia in the extreme northeast section of the basin on 12 November 2020, just before the official start of the season, which marked the third season in a row in which a tropical cyclone formed before the official start of the season. It officially began on 15 November 2020, and ended with the dissipation of Cyclone Jobo on 24 April, 6 days before the official end on 30 April 2021, with the exception of Mauritius and the Seychelles, which officially ended on 15 May 2021. These dates conventionally delimit the period of each year when most tropical and subtropical cyclones form in the basin, which is west of 90°E and south of the Equator. Tropical and subtropical cyclones in this basin are monitored by the Regional Specialised Meteorological Centre in Réunion and unofficially by the Joint Typhoon Warning Center.