Climatology
This page presents Sao Tome and Principe's climate context for the current climatology, 1991-2020, derived from observed, historical data. Information should be used to build a strong understanding of current climate conditions in order to appreciate future climate scenarios and projected change. You can visualize data for the current climatology through spatial variation, the seasonal cycle, or as a time series. Analysis is available for both annual and seasonal data. Data presentation defaults to national-scale aggregation, however sub-national data aggregations can be accessed by clicking within a country, on a sub-national unit. Other historical climatologies can be selected from the Time Period dropdown list.
Observed, historical data is produced by the Climatic Research Unit (CRU) of University of East Anglia. Data is presented at a 0.5º x 0.5º (50km x 50km) resolution.
The climate of São Tomé and Príncipe is tropical with one long rainy season lasting nine months, from September through May, and producing an annual average rainfall of 900 mm. The rainy season is interrupted by a short period termed, “Gravanito”, and occurs during the months of December and January. During this short period, a decrease in rainfall and average air temperature is observed. The occurrence of this intermediate season is dependent on the Inter-Tropical Convergence Zone. A three-month dry season termed “Gravana” lasts from June through August coinciding with the lowest average temperatures of the year. Mean temperatures vary a few degrees throughout the year, ranging between 22°C and 26°C. The lowest average temperatures occur during the dry season months of June through August, while the rainy season experiences higher temperatures.