Local climatology is often used to estimate infiltration losses at the field scale. The objective of this work was to assess the uncertainty associated with such estimates. We computed infiltration losses from the water budget of a soil layer from monitoring data on water flux values at the soil surface and on soil water storage assuming one-dimensional soil water flow. The monitoring data were obtained at the USDA-ARS OPE3 site in Beltsville, MD, where corn was grown on coarse-textured soils with a buried clay lens. The studied focused on a 3.4 ha field instrumented with 12 multisensor capacitance probes to measure soil water content at depths of 30, 50, 80, 120, 150 and 180 cm. Soil moisture and weather data were collected at10 min interval for 18 months. Surface runoff was measured at the field outlet and evapotranspiration was estimated using the FAO methodology. Inspection of the soil water storage time series showed that water budget could be plausibly evaluated over time intervals between local minima on these series. Inspection of correlations between soil water storage increments in soil layers of various depths showed that the water budget of the top 80-cm layer provided practically the same values of infiltration losses for the water budgets calculated from larger depths. Inspection of ratios of the water storage increments to the water influx on the soil surface showed that physically unreasonable values could be obtained if groundwater level changed or intrasoil lateral flow affected soil water storage. Infiltration losses and their coefficients of variation were dependent upon rainfall amount. The intensive soil water, runoff, and weather monitoring provided necessary information to quantify the uncertainty in climatology-based estimates of infiltration losses and will help in the development of a procedure for accurately quantifying hydrologic response at the field scale.