Soil moisture monitoring systems involving correlations with soil dielectric content measured using WCR (water content reflectometer) probes are susceptible to lightning-induced errors during field monitoring programs. These errors must be understood and corrected to use moisture data in geoenvironmental or hydrological applications. This study evaluated the effect of lightning on WCR measurements observed during the monitoring of four evapotranspirative landfill test covers. Several lightning strikes at the site caused unrealistic shifts in the inferred moisture content (from 0.001 to 3.900 m3 m−3), which showed a time-dependent decay. A conceptual model for lightning strike effects was developed that allowed correction of affected WCR data. Because duplicate probes were available in this project, WCR corrections could be calibrated by minimizing the difference between the data from affected probes with data from unaffected probes to within ±5 m3 m−3. This led to a correlation useful in other cases where duplicate probes were not available. Assessment of the consistency of the corrected data included evaluation of wetting fronts, comparison of moisture changes against meteorological patterns, and comparison of the corrected moisture content with upper- and lower-bound moisture content values.