Global warming and urbanization have exacerbated the urban heat island (UHI) effect, threatening human settlements and public health. Existing studies have primarily focused on analyzing urban thermal environment characteristics throughout the year or in specific seasons; however, research examining the urban thermal environment at different stages within a season is scarce. This study employed Local Climate Zone (LCZ) classification and focused on Shenyang, a representative city in China’s severe cold regions. Based on field measurements and multi-source meteorological data, we investigated the differences in thermal environment across seven LCZs throughout summer and at different summer stages. The result show that the UHI effect in Shenyang significantly intensified at nighttime and weakened during the daytime. Built-type LCZs 2 and 4 exhibited the highest nighttime urban heat island intensities (UHIIs), with maximum values of 7.6 °C and 5.4 °C, respectively. The duration of the daytime urban cold island effect in built-type LCZs increased significantly in mid-summer and late-summer. Land cover-type LCZ A exhibited the urban cold island effect only during the daytime throughout the summer. The UHII remained relatively stable across all LCZs during mid-summer. This study provides empirical support for developing targeted heat risk mitigation strategies for cities in severe cold regions.

Most studies have explored the impact of different types of local climate zones (LCZs) on energy consumption, but few have examined climate differences within intra-local climate zones (intra-LCZs) and the impact of cold waves (CW) on energy consumption. This study conducted a 150-day long-term observation of air temperature (Ta) and relative humidity (RH) in six LCZs in Shenyang, a severe cold region, to examine climate differences within intra-LCZs and the influence of CW and the urban heat island (UHI) on energy consumption. The results show that the temperatures and heating energy consumption in 5 LCZ4s exhibited a clear gradient from the urban core to the suburbs. During CW, the differences increased, and the nighttime differences were more pronounced. CW significantly increased residential heating energy consumption, whereas the urban heat island (UHI) reduced it in urban areas. Additionally, there was a clear positive correlation between UHI and the urban-suburban energy consumption difference. Under the combined effects of CW and UHI, the average daily cumulative heating energy consumption in urban areas (CW) was much higher than in suburban areas during non-cold-wave (NCW) periods, increasing by 69.2–85.9%. This study provides empirical evidence for energy conservation and strategies for responding to extreme weather events.