Increased Tropical Cyclone Activity in the Southern Hemisphere, February 2025
In late February 2025, the South Pacific and Indian Oceans experienced simultaneous tropical cyclones, with five storms identified from satellite imagery. Cyclone Rae was weakening after affecting Fiji, while Alfred and Seru posed risks to Australia. In the Indian Ocean, Honde and Garance threatened Mauritius, leading to airport closures. Meteorologists attributed the activity to warm sea temperatures and weak wind shear, portending a higher likelihood of severe cyclones this season.
In late February 2025, both the South Pacific and Indian Oceans experienced a notable increase in tropical cyclones. A rare occurrence saw three storms active in the South Pacific while three additional cyclones stirred in the nearby Indian Ocean. A false-color image acquired by the NOAA-20 satellite on February 26 revealed five tropical cyclones, displaying infrared signals to differentiate between cooler cloud structures and warmer surfaces below.
Among the storms, Tropical Cyclone Rae was weakening east of the captured area after causing substantial rainfall in Fiji. In the South Pacific, Cyclones Alfred and Seru were also present, with Seru reaching Category 1 strength temporarily. While Alfred was expected to cause hazardous coastal conditions for southern Queensland, it was at a Category 2 status but forecasted to intensify to Category 4 shortly thereafter.
Off the coast of Western Australia, Tropical Cyclone Bianca had recently weakened to tropical storm status after intensifying to Category 3 but remained distant from land, thus not posing a direct threat to mainland Australia or surrounding islands. In contrast, Cyclones Honde and Garance, active in the Indian Ocean, presented greater threats to land, particularly prompting the closure of airports in Mauritius as Garance approached.
Meteorologists attributed the surge in tropical cyclones to factors including elevated sea surface temperatures and weak wind shear conditions. A persistent marine heatwave off Western Australia since September 2024 and abnormally high temperatures in late February contributed to these storms. The Australian Bureau of Meteorology had indicated an increased likelihood of severe tropical cyclones this season due to the warm ocean temperatures prevalent during the Southern Hemisphere’s cyclone season, which typically spans from November to April.
The phenomenon of multiple tropical cyclones in the Southern Hemisphere in late February 2025 is attributed to various meteorological factors, including warm sea temperatures and low wind shear. Cyclones Alfred, Seru, Bianca, Honde, and Garance notably affected surrounding regions, with specific alerts issued due to their intensities. This season is characterized by heightened cyclone activity, highlighting the impact of climate conditions on weather patterns.
Original Source: earthobservatory.nasa.gov
