We assess the effect of uncertainty in water vapor continuum absorption on radiative forcing F, longwave feedback λ, and climate sensitivity S at surface temperatures Ts between 270K and 330K. We calculate this uncertainty using a line-by-line radiative-transfer model, assuming moist-adiabatic temperature profiles, 80% relative humidity, and spectrally uniform variations in continuum absorption of ±10%. At Ts=288 K this uncertainty translates to uncertainties of ±0.02Wm−2 (±0.5%) in F and ±0.04Wm−2K−1 (±2.5%) in λ, respectively. Both F and λ weaken for a stronger continuum, inducing opposite effects on S. The weaker λ dominates, causing S to increase by 0.05K (2%) for a stronger continuum at Ts=288 K. Overall, the effect of uncertainty in water vapor continuum absorption on F, λ and S is small compared to the major sources of uncertainty but of comparable magnitude to other uncertainties affecting the relatively well-constrained longwave clear-sky S.