Temperature data collected in shallow estuarine sediments are used to calculate rates of groundwater discharge into the White Oak River in coastal North Carolina. Time series measurements recorded over a period of four months and modeled using numerical solutions to the advection-diffusion equation demonstrate that sediment thermal structure is not explained by purely conductive heat transport. The results of models that assume upward groundwater advection from an underlying source closely mimic field observations of sediment temperature profiles, verifying that thermal data can be used to monitor groundwater discharge. Thermal data is inexpensive and relatively easy to collect, and may be useful for quantifying groundwater flux in areas where low volumes of discharge cannot be detected by direct observation. An advantage of this technique is that it can provide insight into temporal variations in groundwater flow rates.