Assessing the impact of El Niño–Southern Oscillation on South African temperatures during austral summer

Using composite analysis, the timing and extent of El Niño–Southern Oscillation (ENSO) impacts on maximum ( T max ) and minimum temperatures ( T min ) during austral summer are investigated for South Africa over the period 1940–2016. Pearson correlation coefficients determined between temperature data at stations within regions indicate that temperature records are coherent. During austral summer, composite analysis exhibits positive T max / T min anomalies for El Niño years while negative anomalies are recorded during La Niña years across all regions of South Africa. Statistical significance of composite average temperature anomalies was determined using the Student's t ‐test. T max for El Niño years are significantly different from the neutral years over the central interior of South Africa for the period 1940–2016. The most notable finding of this study is that El Niño events have had a stronger warming effect during austral summer over many regions in South Africa after the late 1970s, than before. Such an impact has been most prominent over the northern and central interior regions, where, respectively, associated T max record an average of 1.1 °C and 0.73 °C higher values for the period 1979–2016 compared to the earlier period (1940–1978). Chi‐squared statistics indicate that ENSO phases exert a stronger influence on temperatures over the interior of South Africa than along the coast.