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In this study, we present an analysis of warm extremes over monsoonal China (21–45° N, 106–124° E) during the last 600 years based on Chinese historical documents and simulations from the Paleoclimate Modelling Intercomparison Project Phase 3 (PMIP3) and the Coupled Model Intercomparison Project Phase 5 (CMIP5). The Chinese historical documents indicate that extreme warm records become more frequent after ~1650 CE in North China and ~1850 CE in the Yangtze River Valley. Our analyses of two threshold extreme temperature indices also illustrate that warm extremes have become more frequent since the 17th century in North China and the mid-19th century in Yangtze River Valley in good agreement with the changes in warm extremes revealed in the historical documents. This agreement suggests potential mechanisms behind the shift of periods, which should be further investigated in the future.

The snow-cover days over the middle and lower reaches of the Yangtze River (MLRYR) were extracted from Chinese historical documents for the winter of 1620, which includes the beginning of the tenth month of 1620 through the middle ten days of the second month of 1621 in Chinese lunar calendar. By using these records, the winter temperature anomalies compared with the 1961–1990 mean at nine stations were estimated. The results show an average of 50 snow-cover days over the MLRYR ranging from 30 d in Shanghai to 100 d in Jingzhou. The average snow-cover duration was approximately 70 d in Hefei, Huoshan, Nanjing, and Chaohu, and 40–60 d in Anqing, Wuhan, Changde, Changsha, and Jingdezhen. However, Shanghai and southern Jiangsu province had the lowest number of snow-cover days at 30 d. The regional mean winter temperature in 1620 was estimated to be 4.4 °C lower than the 1961–1990 mean. The maximum negative anomaly of −5.7 °C occurred in Jingdezhen, and the minimum anomaly of −3.6 °C was detected in Changsha. Both anomalies were significantly lower than those of the coldest winter during the instrumental observation period.