Seasonal ground frost can strongly limit water infiltration and promote surface runoff at the local scale. However, existing research does not converge toward a unified model of hydrological behavior in seasonally frozen soils. Depending on the study, frozen soils are reported to markedly increase runoff, to affect runoff in an uncertain manner, or to have little impact. Field-based investigations of infiltration in frozen soils remain scarce, and, to our knowledge, the relationship between infiltration rates and in situ ice content has not yet been systematically examined. This knowledge gap largely reflects the technical challenges associated with measuring both ice content and infiltration rates under natural frozen conditions. This study aims to quantify how specific frozen ground characteristics control infiltration rates in two contrasting soil types. Field experiments were conducted in a clayey agricultural field and a sandy clearing using double-ring infiltrometers installed in the preceding fall and sealed with a clay mixture to prevent leakage under frozen conditions. Infiltration was measured under both frozen and unfrozen soil states. Soil ice content, liquid water content, frost depth, and temperature were quantified using in situ sensors and soil sampling. Results reveal strong temporal variability in infiltration rates under frozen conditions, with substantially greater variability in the clay-rich site than in the sandy site. The influence of frozen soil properties—including frost depth, thermal state, and water and ice content—on infiltration was found to be strongly soil-dependent.