The causes of recent dry-wet changes in the East Asian summer monsoon (EASM) area remain unclear, and attribution analysis to anthropogenic influences is hindered by the lack of long-term hydroclimate record. In this study, we build up a tree ring oxygen isotope chronology in Northeast China, which is the longest to date (1568-2021), and use it to reconstruct summer relative humidity (RH) variations in the northern edge of the EASM region. The reconstruction reveals that Northeast Asia experienced dry conditions during the Little Ice Age (LIA), followed by wet conditions in the Current Warm Period (CWP). On the centennial timescale, the warming caused by the increased greenhouse gases since the Industrial Revolution appears to have strengthened the EASM and facilitated a more humid Northeast Asia. Recent drought events in Northeast Asia since the 1950s are not unprecedented compared with those during the LIA. Recent drought is likely influenced by the positive phase of the Pacific Decadal Oscillation (PDO), the negative phase of the Atlantic Multidecadal Variability (AMV), and anthropogenic aerosol emissions. These findings suggest that recent hydroclimate variations likely reflect a complex interplay between natural forcing mechanisms and competing anthropogenic influences, with warming-induced EASM strengthening potentially moderating what would otherwise be more severe drought conditions.