A multivariate empirical orthogonal function (MV-EOF) analysis for 1979–2010 shows that low-level circulation and rainfall over East Asia experienced a significant decadal shift around the mid-1990s. During boreal spring (March–May), the first principal component (PC) of the MV-EOF exhibits a marked decadal change around the mid-1990s, while during boreal summer (June–August) the second PC shows a pronounced decadal shift around the same time. It is further noted that the decadal rainfall change over southern China experienced an out-of-phase relationship between boreal spring and summer; that is, from the pre-1994 to the post-1994 period, the rainfall tends to decrease in boreal spring but increase in boreal summer. A mechanism is put forward to explain the out-of-phase decadal rainfall change over southern China between boreal spring and summer. In boreal spring, the composite differences of SST between the latter and former decadal periods indicate a La Niña–like pattern with warming in the western Pacific and cooling in the eastern Pacific. This pattern leads the enhanced convection over the Maritime Continent, which may further induce anomalous subsidence and thus negative rainfall anomalies over southern China through the local Hadley circulation. In boreal summer, dominant decadal SST warming appears in the entire tropical Indian Ocean while the negative SST anomalies in eastern Pacific are much weaker. The warm SST anomaly over the Indian Ocean leads to suppressed convection over the Maritime Continent, which, through the local Hadley cell, favors the strengthening the East Asian monsoon trough and leads to a positive rainfall anomaly over southern China.

Amidst the escalating impacts of global warming, the occurrence and severity of compound extreme weather events have risen significantly, presenting substantial threats to both lives and property. Existing response strategies predominantly focus on individual events, often overlooking the cumulative effects rising from their inherent complexity. To address this critical gap, we conducted a thorough examination of sequential extreme precipitation–heatwave compound events (SEPHCE) in China from 1975 to 2020, utilizing data from 1929 meteorological stations. Our investigation revealed a consistent rise in the frequency and duration of SEPHCE, with a particularly notable surge since 1993. Furthermore, shorter interval events disproportionately affected the regions of southwestern and southeast coastal China. Furthermore, SEPHCE onset times exhibited advancement, and the endings were delayed, thereby intensifying the overall trend. These findings underscore the pressing need to prioritize effective planning and adaptation strategies to mitigate the impact of these compound event, while also addressing the potential exacerbation of inequality resulting from climate change.

The present study reveals a close relationship between the leading mode of continental U.S. (CONUS) summer rainfall and the East Asian subtropical monsoon rainfall (viz., mei-yu in China, baiu in Japan, and changma in the Korean peninsula). The East Asian subtropical monsoon rainfall and the CONUS dipole rainfall patterns are connected by an upper-level Asia–North America (ANA) teleconnection. The Rossby wave energy propagates along the path of the westerly jet stream (WJS) from East Asia to North America, affecting the CONUS summer rainfall. Mechanisms through which East Asian summer monsoon heating influence North American rainfall are illustrated by idealized anomaly atmospheric general circulation model experiments. In boreal winter, because of the southward shift of the WJS, the Pacific–North American (PNA) pattern can be excited by the tropical central/eastern Pacific heating associated with El Niño, affecting the rainfall over CONUS. In boreal summer, because the WJS is weaker and locates farther to the north, an equatorial heating anomaly cannot directly perturb the WJS. A perturbation heating over subtropical East Asia, however, can trigger an ANA pattern along the path of the WJS, affecting the rainfall over North America. The season-dependent teleconnection scenario illustrates that the predictability source of CONUS rainfall variability is different between winter and summer. While the PNA pattern generated by El Niño is critical for CONUS rainfall in northern winter, the CONUS dipole rainfall variation in boreal summer is mainly governed by the remote forcing over subtropical East Asia via the ANA teleconnection.

The relationship between the South China Sea summer monsoon (SCSSM) onset and the subsequent subtropical East Asian monsoon rainfall from May to September (SEAMR) is investigated. The SCSSM onset is found to have a significant positive correlation with the SEAMR stretching from the lower reaches of the Yangtze River valley (LYR) to the southern Japan; e.g. the early onset of the SCSSM tends to be succeeded by less SEAMR, whereas the late onset is likely to be followed by more SEAMR. The positive relationship between the SCSSM onset and the SEAMR is directly controlled by the persistent western North Pacific anti‐cyclonic/cyclonic (WNPAC/WNPC) circulation anomaly from boreal spring to summer. The persistence of the large‐scale circulation anomalies are accompanied by the decaying phase of El Niño (La Niña) with the pronounced sea‐surface temperature anomalies (SSTA) over the tropical Indian Ocean (IO), the western North Pacific and the topical central and eastern Pacific Ocean (PO), respectively. Further numerical experiments indicate that the topical IO SSTA governs the positive relationship between the SCSSM onset and the subsequent SEAMR. On one hand, the wavelength of the Kevin‐wave response to tropical IO SSTA forcing is three times that of the Rossby‐wave response to the western North Pacific SSTA forcing. The Kevin‐wave response directly influences the low level circulation anomalies field throughout the South China Sea region, determining the onset date of the SCSSM. On the other hand, the horizontal wind shear that induced by the persistent Kevin‐wave response would also maintain the WNPAC/WNPC and further control the SEAMR from May to September. Thus, it is the topical IO SSTA forcing that consolidates the positive relationship between the SCSSM onset and the SEAMR.