Ava caused at least $195 million (2018 USD) or 744 billion ariary of damage, which was also driven by impacts of the seasonal monsoon which already brought periods of heavy rain and flash flooding in portions of the country.

Conditions were expected to steadily become more favorable for some degree of tropical cyclogenesis as an active Madden–Julian oscillation (MJO) pattern settled over the basin and low level convergence increased on the system's northern side.

[1] Deep convection began to persist near the circulation, and ground observations from Tromelin Island on January 2 indicated the system's low-level center was becoming more well defined.

[1] Conditions were considered relatively favorable for rapid intensification due to insignificant wind shear and strong poleward and equatorward low-level convergence.

[8] A scatterometer pass at the beginning of January 3 revealed a large swath of 65 km/h (40 mph) winds in the northern side of the depression's circulation, warranting an upgrade from MFR to Moderate Tropical Storm Ava at around 06:00 UTC that day, about 300 km (190 mi) east of Antalaha;[9] post-season analysis showed the system had already reached this intensity at 18:00 UTC the day before.

[1] Ava made landfall on Toamasina around 16:00 UTC on that same day at peak intensity, before quickly weakening back down to the equivalent of a tropical storm as the eye and eyewall collapsed.

[17] Ava began a brief period of re-intensification as it drifted south-southeast away from Madagascar while conditions remained slightly favorable,[18] with the central pressure falling back down to 987 hPa (29.15 inHg).

[1] A day after, increasing southwesterly shear began to weaken the storm again and displace the thunderstorm activity well away from the center, while ocean heat content became insufficient.

[22][23] Shortly before making landfall on Madagascar, a station in Toamasina recorded sustained winds of 120 km/h (75 mph) with a pressure of 966.5 hPa (28.54 inHg) before being obstructed, agreeing with the intensity consensus.

[32] The Ambatovy mine, one of the world's largest sources of nickel and located in a rainforest around 200 km (120 mi) away from the city was shut down from operation because of considerable damages to facilities and equipment.

United Nations Children's Fund also provided medical supplies, educational kits, nutritional goods, hygiene products and disinfection of wells for people in these impacted regions.