Evidence of urban heat island impacts on the vegetation growing season length in a tropical city

•Tropical urban phenology has key differences to temperate urban phenology.•In Kampala, growing season length increases along the urban–rural gradient.•Vegetation in the most built-up LCZ class had the shortest growing seasons.•Increases in surface temperatures resulted in shorter vegetation growing seasons. Knowledge about the impacts of urban heat islands (UHI) and associated thermal gradients on vegetation seasonality (i.e. phenology) is vital for understanding spatial patterns in vegetation ecosystem functions. However, in contrast to temperate cites, there is little evidence to show how UHI influences landscape phenological processes in the tropics. In this study, we examined vegetation phenological responses to urban form, distance from the city centre and surface temperatures, in the tropical city of Kampala, Uganda. Estimates of vegetation growing season length and land surface temperature were derived from MODIS satellite imagery for multiple years (2013–2015) and urban form was characterised using the Local Climate Zone (LCZ) classification. We showed that growing season length increased along the urban–rural gradient (p