The 1965–66 South-West Indian Ocean cyclone season was a near average season, despite beginning unusually early on August 9 with the formation of an early-season tropical depression, Anne and ended on May 1.

The peak was 30 miles per hour or 45 KM/H.Claude existed from December 24 to January 10.On January 7, Cyclone Denise passed north of Mauritius, producing wind gusts of 170 km/h (110 mph).

Later, the storm crossed over Réunion, dropping record rainfall.

Over a 24-hour period, Denise dropped 1,825 mm (71.9 in) of rainfall at Foc Foc, Réunion, of which 1,144 mm (45.0 in) fell over 12 hours; both precipitation totals are the highest recorded worldwide for their respective durations.

Over 48 hours, precipitation totaled 2,230 mm (88 in) at Bras Sec.