Approaches to fracture prediction based on local stress and toughness use the Weibull distribution model based on weakest link theory. Accuracy of predictions as part of the integrity assessment of structural steels containing defects and often subjected to a thermal and mechanical loading history relies on the precision of distribution parameters. Extensive research work has recently been conducted to characterize the ductile-to-brittle transition (DBT) behavior of ferritic steels. This paper investigates geometry and temperature dependence of distribution parameters and uses the ‘Euro fracture dataset’ to estimate the Weibull parameters in a ductile-to-brittle transition regime. ‘Global’ equations for determination of distribution parameters are then proposed based on calibration to available data.