In this paper, the impact of vegetation and fire on the radiation pattern of a small antenna to be used in a WSN sensor node, is studied. The proposed antenna used in this study is based on a differential patch design, tuned to operate in the 2.4 GHz frequency band. The antenna presents a reduced size of $$45\times 45$$45×45 mm2 (0.36$$\lambda $$λ $$\times $$× 0.36$$\lambda $$λ). The simulations were carried using a full-wave EM solver (CST MWS) considering four different scenarios: the first scenario only containing the antenna placed on the ground to serve as reference; in the second scenario vegetation was introduced to serve as the “normal” state of the terrain surrounding the sensor node; the third scenario includes the impact of surrounding fire considering the permittivity expected during such an event; and the last simulation was performed to include all the previous components simultaneously.