Given the destructive nature of hurricanes, gale force winds and tropical storms it is crucial that potential offshore wind energy projects undergo extensive tests of the site-specific conditions for safety reasons. One of the thirteen chapters of the new "Guideline for the Certification of Offshore Wind Turbines" published by Germanischer Lloyd WindEnergie GmbH (GL Wind) deals exclusively with this site assessment and the resulting loads. The chapter defines the requirements for the determination of loads resulting from the environmental conditions in conjunction with the operational behaviour of an offshore wind turbine. These conditions include peak wind speeds due to storms and rapid changes in wind speed and direction. These extreme conditions include the potential effects of wind turbulence. The offshore guideline covers general testing conditions, safety systems and the requirements for the manufacturing companies. Strength analyses, machinery components and electrical engineering are considered as well as tests requirements, periodic inspections and condition monitoring. So far, a number of projects had already been certified and/or are currently in the certification process according to the new guideline.