How has Shenzhen been heated up during the rapid urban build-up process?

•The urban heating in Shenzhen was studied with three other cities in SE China.•Temperatures increased significantly during 1961–2010 with higher rate after 1985.•Nighttime and winter temperatures increased more than other temperature measures.•The land use changes explained the warming differences among the four cities.

Urban heat island (UHI) has been widely reported as a common environmental phenomenon in urban landscapes. We used the long-term climatic records of 1961–2010 in the Shenzhen Economic Zone (SEZ) and compared temperature differences with Shantou (ShT), ShanWei (ShW), and YangJiang (YJ) to assess the heating increases at five different times. We calculated the daily mean temperature (Tmean), daily minimum temperature (Tmin), diel temperature ranges (DTR= Tmax − Tmin), the ratio of the SEZ to the three benchmark cities, and examined the relationships between the land use and cover changes and temperature increases. The increases seemed more pronounced for minimal temperatures and in the winter time. These increases, however, varied greatly among the four cities where there existed similar geographic and climatic conditions From pre- to post-1985, the daily mean minimal temperature (Tmin) increased by 1.64 °C for SEZ, 0.92 °C for ShT, 0.59 °C for ShW, and 0.81 °C for YJ, the DTR changes were −1.17 °C, +0.20 °C, −0.07 °C, and −0.45 °C for the SEZ, ShT, ShW, and YJ, respectively. The ratio of the SEZ to the other three cities in Tmin was around zero (0.80–1.10) in the first 25 years, but reached 1–2 in the last 25 years. The tight correlation between land cover change (LCC) and UHI suggests that the UHI can be reasonably predicted.