The present paper deals with on-site measurements and 3D steady RANS simulations performed on the “IJmuiden vault” which falls under the Port Authority of Amsterdam. The numerical results were validated, in terms of amplification factor and local wind direction, using on-site measurements carried out by four 2D ultrasonic anemometers for a period of nine months. To quantify the deviation between measured and simulated data, the metric FAC1.3 was used. In that respect, 90% of simulated data (in terms of amplification factor) was found to be within 30% of deviation from the measured data. In terms of local wind direction, 86% of simulated data were found within ±30° and only the 6% of the whole database showed a large deviation equal and greater than ±60°. Finally, a software application was developed to convert the macroscale wind conditions to the local wind conditions near and in the newly built vault.