This study presents the external wind conditions for the design and assessment of wind turbine loading in tropical cyclone regions, including physical constants, wind speed (cyclone classes), wind shear, turbulence intensity, turbulence length scale and turbulence spectral models. For the extreme condition, this study focuses on the wind characteristics of the cyclone eye-wall region that carries the strongest wind. For the dynamic response of wind turbine structures, it is worth the effort to characterize the size of eddies constituting turbulent wind. The turbulence integral length scale for cyclone wind is defined and validated with various measurements. Moreover, several turbulence spectral models are validated with field measurements and the ESDU von Karman model gives the best fit. Based on the external wind conditions, a new turbulent cyclone wind model is created with the associated load case(s). A state-of-the-art load analysis is performed using this new cyclone wind model and the results for the relevant turbine components are compared with the existing loads envelope. (C) 2014 Elsevier Ltd. All rights reserved.