The performance of communication systems based on free-space optical links depends on external factors such as weather conditions. Among many atmospheric factors, turbulence can be the greatest challenge to performance. The characterization of atmospheric turbulence usually involves expensive equipment known as a scintillometer. This work presents a low-cost experimental setup for measuring the refractive index structure constant over water, which results in a statistical model based on weather conditions. The turbulence variations with air and water temperature, relative humidity, pressure, dew point, and different watercourse widths are analyzed for the proposed scenario.