Dielectric permittivity-water content relationships in woodchips: Particle size and temperature effects

•Woodchips dielectric permittivity measured from dry to 0.83 cm3/cm3 water content.•Significant covariates were particle size (0.03–25.4 mm) and temperature (10–70 °C).•Multivariate power law function relates dielectric permittivity to water content.•Parameter uncertainty quantified within a Bayesian regression framework.•Field validation reveals generalized equations are sufficient for practical usage.