In addition to the named storms, there were several other storms during the season that were warned on.
On September 10, 1991, the JTWC began monitoring a tropical depression in the northeastern portion of the basin.
The system moved southeastward, and according to the agency intensified into an 85 km/h (50 mph 1‑minute sustained) tropical storm on September 12.
By the next day, the storm dissipated after turning back to the north.

About a month after the previous storm dissipated, the JTWC classified another tropical depression on October 11 about 960 km (600 mi) east-southeast of Seychelles.
The system tracked west-southwestward, and the MFR also began issuing warnings on it as Tropical Depression A2 on October 14.
Two days later, the JTWC briefly upgraded the depression to a tropical storm, although MFR only estimated peak 10‑minute winds of 50 km/h (30 mph).
By that time, the storm had turned to the west, passing north of the northern tip of Madagascar.
After turning to the west-northwest, the depression dissipated on October 22.
While the depression was active, the MFR also briefly tracked another tropical depression to its northeast, which formed on October 16 about 540 km (345 mi) south-southeast of Diego Garcia.
Classified as Tropical Depression A3 by MFR, the depression tracked to the west-southwest, turned to the southeast, and resumed its westward trajectory for several days before dissipating on October 22.

On November 20, the JTWC began tracking Tropical Cyclone 04S a short distance southeast of Diego Garcia.
The next day, MFR also initiated advisories on it, classifying the system as Tropical Depression A4.
After moving southwestward initially, the storm curved south-southeastward and intensified.
The JTWC estimated peak 1‑minute winds of 85 mph (50 mph), and the MFR estimated 10‑minute winds of 65 km/h (40 mph), indicating that it could have been named.
While near peak intensity, the storm was affected by wind shear that displaced the circulation center along the north edge of the convection.
The storm turned to the west, passing just south of St. Brandon before dissipating on November 29.

While storms Farida and Gerda were both active, Tropical Depression H1 formed east of Madagascar on February 26, and throughout its duration moved in a circular direction around Gerda.
The depression moved to the east but slowly executed a clockwise loop around St. Brandon.
It never intensified beyond winds of 55 km/h (35 mph), and dissipated on March 1.
On March 7, the MFR identified a subtropical cyclone in the Mozambique Channel, but did not issue warnings on it.
In addition to the named storms, there were several other storms during the season that were warned on. On September 10, 1991, the JTWC began monitoring a tropical depression in the northeastern portion of the basin. The system moved southeastward, and according to the agency intensified into an 85 km/h (50 mph 1‑minute sustained) tropical storm on September 12. By the next day, the storm dissipated after turning back to the north.
About a month after the previous storm dissipated, the JTWC classified another tropical depression on October 11 about 960 km (600 mi) east-southeast of Seychelles. The system tracked west-southwestward, and the MFR also began issuing warnings on it as Tropical Depression A2 on October 14. Two days later, the JTWC briefly upgraded the depression to a tropical storm, although MFR only estimated peak 10‑minute winds of 50 km/h (30 mph). By that time, the storm had turned to the west, passing north of the northern tip of Madagascar. After turning to the west-northwest, the depression dissipated on October 22. While the depression was active, the MFR also briefly tracked another tropical depression to its northeast, which formed on October 16 about 540 km (345 mi) south-southeast of Diego Garcia. Classified as Tropical Depression A3 by MFR, the depression tracked to the west-southwest, turned to the southeast, and resumed its westward trajectory for several days before dissipating on October 22.
On November 20, the JTWC began tracking Tropical Cyclone 04S a short distance southeast of Diego Garcia. The next day, MFR also initiated advisories on it, classifying the system as Tropical Depression A4. After moving southwestward initially, the storm curved south-southeastward and intensified. The JTWC estimated peak 1‑minute winds of 85 mph (50 mph), and the MFR estimated 10‑minute winds of 65 km/h (40 mph), indicating that it could have been named. While near peak intensity, the storm was affected by wind shear that displaced the circulation center along the north edge of the convection. The storm turned to the west, passing just south of St. Brandon before dissipating on November 29.
While storms Farida and Gerda were both active, Tropical Depression H1 formed east of Madagascar on February 26, and throughout its duration moved in a circular direction around Gerda. The depression moved to the east but slowly executed a clockwise loop around St. Brandon. It never intensified beyond winds of 55 km/h (35 mph), and dissipated on March 1. On March 7, the MFR identified a subtropical cyclone in the Mozambique Channel, but did not issue warnings on it.
1991–92 South-West Indian Ocean cyclone season