Against the backdrop of frequent extreme weather events caused by global warming, research on the characteristics and causes of summer climate anomalies in China is of great significance. Based on data from China's national meteorological observation stations and ERA5 reanalysis data, this study identified regional high-temperature, heavy rainfall, and other events using objective and quantitative methods. The paper focused on analyzing the temporal and spatial characteristics as well as hydrothermal properties of five high-temperature events in typical provinces in northern China, and diagnosed their causes through the column-integrated water vapor budget equation. Data analysis and evaluation reveal that the national average temperature in summer 2025 reached a record high, with precipitation showing a distribution pattern of "rainy in the north and south, dry in the center". High-temperature events in northern China exhibited significant phased differences: June saw dry-heat events, while July-August witnessed the evolution into extreme compound hydrothermal events characterized by long duration, wide scope, high intensity, and superimposed high humidity. Cause analysis indicates that the high temperatures in July-August were directly related to the increased downward longwave radiation induced by enhanced total column water vapor. Additionally, water vapor transport was affected by the water vapor convergence in the periphery of the anomalously strong Western Pacific Subtropical High (WPSH) that shifted westward and northward. This study reveals the evolutionary characteristics and physical mechanisms of the 2025 summer climate anomalies and high-temperature events in northern China, providing a typical case and a new perspective for understanding the rules of regional extreme events against the background of global warming.