The Indonesian Throughflow (ITF) transports relatively warm, and fresh waters into the Indian Ocean. These waters traverse the basin embedded within the westward-flowing South Equatorial Current (SEC), strongly influencing heat content, vertical stratification, and form a key link in the global exchange of water masses. Although the seasonal pathways of the SEC are well established, the interannual variability remains less und...

Tropical cyclones are among the most destructive weather systems, yet prediction skill in the South-west Indian Ocean (SWIO) lags due to limited observations and modelling constraints. This study evaluates the Conformal-Cubic Atmospheric Model (CCAM) in simulating track and intensity of Tropical Cyclone Idai, relative to the operational Unified Model (UM) at the South African Weather Service (SAWS). Simulations were performed...

More than half of La Niña occurrences are multiyear events, lasting for at least two consecutive summers and tend to be associated with above average summer rainfall over southern Africa. Over southeastern Africa, it is found that double year events exhibit wet conditions much less consistently than triple year events during mid to late austral summer. Here, seasonal and sub-seasonal composites of atmospheric fields are used t...

The multiyear La Niña event of 2020–2023, which brought with it several climate disasters across the globe, sparked both mainstream and scientific interest in La Niña events, which typically have received less attention than El Niño. In southern Africa, there is a general expectation in the scientific community and among user groups that La Niña events result in cool and wet summers. However, such impacts do not always occur a...

Prolonged marine heatwaves (MHWs) around small island developing states can lead to severe ecological and socio-economic consequences. This study aims at characterizing subsurface MHWs and their potential drivers around the Seychelles and Comoros, rich in biodiversity and prominent to tropical cyclone intensification. Both regions show intensified MHWs in the thermocline, but with a higher intensity and duration in Seychelles....

Changes in late summer (January to March) rainfall over the eastern Congo Air Boundary (CAB) region in southern Africa are examined. Using ERA5 data for the 1979–2024 period, a significant increasing trend in rainfall totals is found over most of the region which results from an increase in the number of heavy rain days (10 mm or more). On the other hand, there has been a significant decreasing trend in light rain day numbers...

Although the El Niño-Southern Oscillation (ENSO) is the leading mode of climate variability in southern Africa during the austral summer season, the impacts are nonlinear and not all events result in the expected impact. Limited work has been carried out to explore the role ENSO diversity plays in southern African climate, which this study aims to address. Here, the influence of El Niño diversity on rainfall characteristics an...

The topography of Madagascar and the strength of the Mozambique Channel Trough (MCT) modulate summer rainfall over southern Africa. A strong MCT hinders the penetration of moisture bearing easterlies from the South Indian Ocean into the mainland, thus reducing rainfall there and vice versa for weak MCT summers. Given the link between the MCT and rainfall, it is important to analyse how climate models represent the trough. Here...

Linear-regime westerly waves that propagate across the South African domain are often linked to well-known rainfall producing systems such as tropical temperate troughs and synoptic scale tropical low-pressure systems, and ridging South Atlantic Ocean anticyclones at the surface. It is accepted that the baroclinic waves that propagate across the domain provide the lifting mechanism that causes the required vertical motion for...

The Okavango River Basin (ORB), including the World Heritage site Okavango Delta, is a region of high biodiversity projected to suffer increased early summer drying under climate change. Little work has been done on drought over this sensitive region. Here, various drought metrics are analysed over the ORB. These include a cumulative drought intensity index, based on the product of maximum temperature anomaly and maximum durat...

Ridging South Atlantic high pressure systems (ridging highs) are often accompanied by cut-off low (COL) pressure systems aloft, but may also occur without them, in which case a linear baroclinic wave would be observed propagating across the South African domain in the upper troposphere. Using 41 years of ERA-5 reanalysis data, this study documents differences between the characteristics of the prevailing dynamical processes an...

Mozambique is highly dependent on subsistence agriculture. Thus a climatology of rainfall onset and cessation is derived together with their interannual variability and trends using gridded daily data and station data. Mean onset is found to occur from early to mid‐November over southernmost regions, mid‐ to late November over central regions and late November to early December over the northern and coastal regions while cessa...

The Okavango River Basin (ORB) is a highly sensitive and biodiverse region in southern Africa whose climate, vegetation and river discharge characteristics are not well understood. This study investigated relationships between rainfall, temperature, Normalized Difference Vegetation Index (NDVI) and river discharge over the region as well as their trends and interannual variability. It is found that spatial patterns of NDVI are...

Atmospheric forcing and climate modes of variability on various timescales are important drivers of sea level variability. However, the influence of such drivers on sea level variability along the South African east and south coast has not yet been adequately investigated. Here, we determine the timescales of sea level variability and their relationships with various drivers. Empirical Mode Decomposition (EMD) was applied to s...