The summer climate of tropical North Africa exhibits strong decadal variability (the low frequency, LF) and also substantial variability within the decadal regimes (the high frequency, HF). Statistical analyses on raw climate data can confound processes on the HF and LF or be overwhelmed by the decadal scale. In this paper, the HF and LF are studied separately. In recent decades, the LF in tropical North Africa is dominated by decreasing rainfall, strongest in summer months, but not absent in the transition seasons. The known change in the north–south interhemispheric gradient of sea surface temperature (SST) has accompanied climate fluctuation not just in the Sahel, but through much of the Tropics, including a modest decline in July–September (JAS) Indian rainfall. These large-scale changes of the ocean and atmosphere are consistent with a coupled ocean–atmosphere phenomenon, though results are also discussed in terms of a possible role for land surface changes in tropical North Africa. On the H... Abstract The summer climate of tropical North Africa exhibits strong decadal variability (the low frequency, LF) and also substantial variability within the decadal regimes (the high frequency, HF). Statistical analyses on raw climate data can confound processes on the HF and LF or be overwhelmed by the decadal scale. In this paper, the HF and LF are studied separately. In recent decades, the LF in tropical North Africa is dominated by decreasing rainfall, strongest in summer months, but not absent in the transition seasons. The known change in the north–south interhemispheric gradient of sea surface temperature (SST) has accompanied climate fluctuation not just in the Sahel, but through much of the Tropics, including a modest decline in July–September (JAS) Indian rainfall. These large-scale changes of the ocean and atmosphere are consistent with a coupled ocean–atmosphere phenomenon, though results are also discussed in terms of a possible role for land surface changes in tropical North Africa. On the H...