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The nonstationary roles of regional forcings from alongshore wind stress and sea level pressure (SLP) in driving low‐frequency (interannual‐to‐decadal) sea level variability along the U.S. east coast for the 1959–2020 period are investigated. The role of regional forcings increases with time north of Cape Hatteras particularly during summer when their contributions to the variance of observed summertime coastal sea level anomalies increase by approximately 58%–87% from 1959–1989 to 1990–2020. The enhanced impact of regional forcings in recent decades results from an increase in the Inverted Barometer (IB) effect that act constructively with alongshore wind stress especially during summer, and to a lesser extent for the Gulf of Maine during fall. The summertime North Atlantic Oscillation (NAO) is largely responsible for the increased IB effect, owing to the stronger NAO‐associated low SLP anomalies centered around the Mid‐Atlantic Bight in recent decades compared to earlier decades. Plain Language Summary: Alongshore wind stress and sea level pressure (SLP) are important regional forces in driving low‐frequency (interannual‐to‐decadal) sea level anomalies along the U.S. east coast. The roles of these regional forcings, however, vary with time, season, and region, which can shift the location and change the frequency and intensity of coastal flooding. In this study, we find that regional forcings contribute more to observed sea level variability north of Cape Hatteras in recent decades (1990–2020) compared to earlier decades (1959–1989), particularly during summer. The increased role of regional forcings results from SLP variability via the Inverted Barometer (IB) effect, which exhibits a significant upward trend during summer with lower (higher) SLP raising (suppressing) sea level. The North Atlantic Oscillation (NAO) is largely responsible for the increased role of IB effect because the lower SLP anomalies related to the NAO have become more prominent north of Cape Hatteras in recent decades. Although winter NAO has been shown to be important for affecting the coastal sea level anomalies, it is the summer NAO effect that is enhanced via the IB effect, accounting for the enhanced regional forcing in recent decades. Key Points: The sea‐level variance explained by regional forcings increases with time north of Cape Hatteras due to the Inverted Barometer effectLower sea level pressure centered around Mid‐Atlantic Bight favors more contributions of the Inverted Barometer effect in recent decadesThe summertime North Atlantic Oscillation is largely responsible for the increased role of the Inverted Barometer effect [ABSTRACT FROM AUTHOR]