Numerical simulation and modeling have shown that wind farms have an impact on near-surface meteorology. However, with the exception of a few observa-tional data sets that lack high spatial resolution, little to no observational evi-dence exists. To validate numerical simulation and modeling, and create multi-ple high resolution data sets, an instrumented small unmanned aerial system (sUAS) was used to differentially map downstream changes to temperature and relative humidity in two state-of-the-art wind farms. A sUAS fills an important gap in the suite of instruments available for investigation of the lowest layer of the atmosphere, termed the atmospheric boundary layer (ABL). Conventional, manned aircraft are unable to operate within the ABL due to a myriad of safety concerns. While meteorological towers can be erected here and are able to pro-vide high temporal resolution and accuracy, they cannot provide high spatial resolution and have practical height limitations that are well below the height of the ABL. Tethered solutions can only offer skewed single column measurements and similar non-tethered options cannot be precisely controlled. Remote sensing solutions also possess altitude limitations and decreasing resolution with height. As a result of these limitations, the aforementioned strategies do not offer in-sight into horizontal inhomogeneity or a complete description of the vertical ex-tent of the ABL. Alternatively, a sUAS can be precisely controlled to provide horizontally and vertically continuous measurements across vast heights (includ-ing the vertical extent of the ABL) and distances conveniently and cost effec-tively. Following the obtainment of the requisite exemptions and authorization from the FAA, a small quadcopter-style unmanned aerial system was developed with an instrumentation mount, temperature and relative humidity sensors, a mi-crocontroller, GPS receiver, SD card module, and a power source for data log-ging and the powering of sensors. Following flight-testing, a variety of profiles were flown in the near wake region of two different utility-scale wind turbines. Measured values were compared to corresponding upstream values. Wind tur-bines are found to differentially alter the temperature and relative humidity in the downstream, spanwise and vertical directions under a variety of atmospheric stability conditions, and a sUAS was found to be a viable option for safe, effi-cient and economical in-situ atmospheric data measurement.