Tropical Cyclone Freddy is now the Southern Hemisphere’s strongest tropical cyclone on record based on the total amount of energy this two-week old system has used in its lifetime.

The Accumulated Cyclone Energy (ACE) index is a relatively new metric that measures how much energy a tropical cyclone uses over its entire lifetime. The ACE takes both the duration of a cyclone and its intensity into account, which provides a holistic measure of the storm beyond just its peak wind speed or lowest central pressure.

Duration and strength can both pump up the ACE value for an individual tropical cyclone, and Freddy has had both of these in spades.

Freddy first became a tropical cyclone off the northwest coast of Australia on Saturday, February 4. After traversing the entire Indian Ocean over the last fortnight, the system is on track to make landfall along the east coast of Madagascar late on Tuesday, February 21. Freddy will have travelled more than 7,000 km by the time it hits Madagascar.

Video: This incredible footage of Tropical Cyclone Freddy was captured from the International Space Station on Friday, February 17. It shows a clear view of the Indian Ocean through the eye of the cyclone, along with rib-like bands of convective clouds with overshooting tops in the eyewall. Source: ISS Above / NASA

At its peak, Tropical Cyclone Freddy was estimated to have been generating sustained 10-minute wind speeds of 220 km/h (140 mph) near its core, with 1-minute wind speeds of around 270 km/h (165 mph). This is equivalent to a category 5 hurricane, making Freddy one of only five category 5 hurricane-strength systems ever recorded anywhere on Earth during February.

With such high numbers for longevity and strength, it’s no surprise that Freddy has produced a large ACE rating.

At of 22:00 GMT on February 19 (09:00 AEDT on February 20), Freddy had an ACE of 56.6, according to Colorado State University’s Department of Atmospheric Science. This is the Indian Ocean’s highest single-storm ACE in records dating back to 1980, beating the previous record of around 53 from Tropical Cyclone Fantala in 2016.

According to Meteo-France, Tropical Cyclone Freddy is expected to make landfall along the east coast of Madagascar on Tuesday night, most likely somewhere between Nosy-Varika and Mananjary at this stage. You can check the latest tropical cyclone advisories from Meteo-France here.