Spatial and temporal variability in global, diffuse, and horizontal direct irradiance and sunshine duration has been evaluated at eight stations in South Africa and two stations in Namibia where the time series range between 21 and 41 years. Global and direct irradiance and sunshine duration decrease from northwest to southeast; diffuse irradiance increases toward the east. Annually averaged global irradiance G_a decreased between 1.3% (2.8 W m⁻²) and 1.7% (4.4 W m⁻²) per decade at Bloemfontein, Cape Town, Durban, Pretoria, and Upington. Annually averaged diffuse irradiance D_a decreased 5.2% (3.0 W m⁻²) per decade at Grootfontein and 4.2% (3.1 W m⁻²) per decade at Port Elizabeth. Annual direct irradiance B_a decreased 2.1% (3.5 W m⁻²) per decade at Cape Town and 2.8% (5.7 W m⁻²) per decade at Alexander Bay. A simultaneous decrease in annually averaged daily sunshine duration S_a may have contributed to the decrease in B_aat Alexander Bay and the decrease in G_a at Pretoria. Increases in aerosols may have contributed to the observed decrease in G_a at Cape Town and Durban, and the decrease in D_a at Grootfontein may be due to a decrease in aerosols. On average, variability in S_aexplains 89.0%, 50.4%, and 89.5% of the variance in G_a, D_a, and B_a respectively. The radiative response to changes in sunshine duration is greater for direct irradiance than for global and diffuse. In the 2 years following the 1963 Mount Agung eruption in Indonesia, changes in global irradiance over southern Africa were small and inconsistent. At eight stations, diffuse irradiance increased 21.9% (13.3 W m⁻²) on average and direct irradiance decreased 8.7% (15.5 W m⁻²). After the 1982 El Chichón eruption in Mexico, global irradiance increased at two stations and decreased at seven stations. Eight stations witnessed an increase in diffuse irradiance averaging 7.2% (4.0 W m⁻²) and a decrease in direct irradiance of 5.0% (9.0 W m⁻²). The contribution of changes in cloud cover to the observed changes in irradiances appears to be small. Following the 1991 Mount Pinatubo eruption in the Philippines, diffuse irradiance increased an average of 18.8% (10.0 W m⁻²) at three stations and direct irradiance decreased by 7.2% (13.0 W m⁻²). Keywords: solar radiation, climate change, volcanic, volcano, southern Africa, South Africa, Namibia.