Leaf flushing in temperate trees has been well studied, and these studies showed that the timing of leaf flushing is regulated by seasonal changes in environmental factors, such as temperature and light. In tropics, long-term phenological studies also suggested correlations between the seasonal trends of leaf flushing of several trees and fluctuations in environmental factors. However, it remains unclear whether leaf flushing in tropical trees is regulated by such environmental factors because of the lack of empirical data. To understand the effects of environmental factors on the regulation of leaf flushing in tropical trees, we conducted an interdisciplinary study in Forest Research Institute Malaysia (FRIM), focusing on the family Dipterocarpaceae. Firstly, we performed a whole-genome transcriptome analysis, and the results suggested that leaf flushing in dipterocarp species might be regulated by temperature. We then monitored the timing of leaf flushing using dipterocarp seedlings at FRIM’s nursery and found that leaf flushing tends to occur under higher temperature conditions. Finally, we conducted a growth chamber experiment, and more individuals showed leaf flushing under the higher temperature conditions in the chamber. These results suggest that the timing of leaf flushing in dipterocarp species is regulated by small fluctuations in temperature.