During a major storm event, a breach in the exterior envelope of an arena is possible. Review of these events in the past has indicated that a breach is most likely due to the impact of projectiles from the area surrounding the site unless impact resistant materials are used. A large enough opening could lead to high internal pressures which would add to the values considered for the design of structure and cladding elements. Building codes and standards generally have provisions for calculating internal pressures through simple formulae. However, wind loads can vary greatly for different shapes and orientations of the exterior envelope. Therefore, it is a very difficult task for simple methods to address all of the combinations of conditions that can occur. Additionally, the large interior volume of an arena reduces the response of the internal pressure to wind gusts on the exterior. This paper illustrates the use of wind tunnel tests to estimate the internal pressures in such cases, more precisely.