The Usambara Mountains are a region in Tanzania with a
high population density, low soil fertility and high rainfall
variability. The persistence of drought occurrence and the
influence of the Indian Ocean Dipole (IOD) driven sea
surface temperature (SST) anomalies on drought
occurrence in the Usambara Mountains was analyzed. A
Markov analysis was used to calculate the rainfall
probabilities and drought occurrence. The OctoberDecember
rainfall season showed a higher rainfall
variability than the March-May rainfall season, a higher
probability for drought occurrence, is therefore unreliable
for the cultivation of crops and is correlated with the IOD