Early in March 2020, an area of low pressure existed near Tromelin Island, but it dissipated on 4 March. It unexpectedly regenerated the next day near the Mascarene Islands. Météo France predicted it would strengthen into a tropical depression by the end of the week. Over the next two weeks, it gradually gained convection, until on 13 March, Zone of Disturbed Weather 10 formed northwest of Madagascar. The next day, the JTWC and MFR upgraded it to a tropical depression. Late on 14 March, 10 reached moderate tropical storm intensity and was named Herold. The JTWC began tracking it as Tropical Cyclone 22S. Herold began to undergo slow intensification. At 18:00 UTC on 15 March, the cyclone was designated Tropical Cyclone Herold. Late on March 17, Herold reached its peak intensity as an Intense tropical cyclone, and the JTWC classified it as a Category 3-equivalent tropical cyclone. As this happened, Herold rapidly moved southeast, Herold's peak intensity was short-lived. On 18 March, Herold began rapidly weakening. Later that day, Herold became extratropical. Finally, on 20 March, Herold dissipated entirely.
Preparations
Madagascar
The first alert, a green alert, was issued on March 13 by Météo Madagascar for the areas in northeastern Madagascar. The next day, the alert was upgraded to a yellow alert.
Mascarene Islands
On 18 March, a class four cyclone warning was issued for Rodrigues.
Impact
Madagascar
Heavy rain was recorded in northeastern Madagascar on 13 March. 95 mm fell on Sambava that same day. Intense flooding occurred in the Ankavanana River, which threatened more than 1000 people. Five people were killed in the Sava Region. Flooding impacted more than 100 schools. Homes were swept away in areas near Maroantsetra. Near the Andranofotsy River, people were most affected. By 17 March, though, the water level had decreased a fair amount in the community. That day, the water level on land rose to 2 meters. 13 of 20 municipalities in the Maroantsetra district were underwater and 28 houses had been destroyed in the town of Mahalevona. In Maroantsetra, 104 homes were affected by the storm surge. A school in Anjanazana was found with puddles of mud in its classrooms. The effects of Herold didn't end until the cyclone alerts were lifted on 17 March for the entire island. 911 homes were flooded. 178 huts were damaged, and 127 residencies were destroyed in Madagascar. In Maroantsetra, 79 classrooms were damaged, and 24 were damaged in Sainte-Marie.
Mascarene Islands
In the Mascarene Islands, maximum sustained winds of 185 km/h was recorded. When Herold passed in between the islands of Mauritius and Rodrigues on 17 March, it made schools close and caused eighty people to seek refuge in accommodation centers. In the islands, damage was minimal. In most areas, it was limited to downed trees and power outages. However, a gust of 130 km/h was recorded in Sir Gaëtan Duval Airport. Maximum rainfall was no more than 29 mm. Herold also briefly passed over Réunion. There was no known damage there.
