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The urban heat island (UHI) is a major topic in the study of urban climates. However, comprehensive research on the atmospheric UHI (UHI Atm), surface UHI (UHI Surf), and subsurface UHI (UHI Sub) simultaneously has yet not been reported. Using the MODIS land surface temperature and atmospheric profile data during the 2010–2016 period, we investigated the diurnal, seasonal, and vertical variations of UHI Atm , UHI Surf , and UHI Sub in Beijing. The major findings include but are not limited to the following: As the altitude increases from 1000 hPa (near the surface) to 700 hPa (~3 km), the daytime UHI Atm intensity in summer decreases piecewise linearly with a rapid decline above 850 hPa (~1.5 km), while in spring and autumn it decreases after a slight increase in the lower atmosphere. The nighttime UHI Atm intensity decreases approximately linearly in all seasons with a rapid (gradual) decline in winter (summer). As the depth increases from the surface to ~0.2 m, the daytime intensity from UHI Surf to UHI Sub decreases in summer but increases in the other seasons, while the nighttime trends are opposite to the daytime ones. The diurnal (seasonal) variation of UHI Sub intensity converges to the daily (annual) mean as the depth reaches ~0.5 m (10 m). These new findings have theoretical and practical implications for in-depth understanding of the urban thermal environment from the boundary layer to the subsurface. • Vertical profiles of UHI Atm , UHI Surf , and UHI Sub were characterized. • Relationships of UHI Atm and UHI Sub relative to UHI Surf were explored. • UHI Atm intensity shows distinct diurnal and seasonal variations with altitude. • UHI Sub intensity shows opposite variations with depth during the day and night. [ABSTRACT FROM AUTHOR]