Today, traditional drone testing techniques are of poor quality and do not reflect conditions that may be encountered in real world applications. Drones are either flown outdoors in not well documented, uncontrolled and unpredictable weather conditions (and quite remote from the observer), or tightly strapped onto a support in a conventional wind tunnel with laminar and uniform wind flows. Such wind flows have been devised for conventional aircraft and are inadequate representations of atmospheric conditions relevant to drones. In order to test drones in various and controllable atmospheric conditions, a real weather simulator was developed. The wind and weather facility (windshaper) consists of an array of a large number of fans that may be arranged in various patterns according to need. It subjects drones to winds of variable intensity and direction as well as various weather conditions (such as rain, snow, hail, fog etc.) that reflect real world situations. These tests can rate drones according to their capacity in maintaining a proper flight attitude and tackling flight perturbations in an urban, countryside, or high altitude environment. In order to achieve these goals, a windshaper needs to replicate real environmental conditions. To do so, two key steps are to be undertaken: 1. document actual atmospheric turbulence at drone scales (in particular in an urban environment), and 2. develop a methodology to reproduce these flows in a windshaper. Using a three-component hot-wire anemometer (HWA), a complete flow characterisation of a windshaper has been performed to evaluate the flow modulation capabilites of these new types of wind generating facilities. The HWA was then used to collect a series of high-frequency outdoor measurements on a city rooftop. The measured outdoor velocity time history and its spectral content have then been replicated at actual scale in a windshaper by using an iterative algorithm in the frequency domain.