In addressing the issue of path planning for UAVs (unmanned aerial vehicles) in plateau forest fire extinguishment, a three-dimensional geographic spatial model is constructed using a grid-based approach based on DEM (digital elevation model) data. The impacts of altitude, ambient wind, and fire temperature on UAV performance were analyzed. A UAV path planning model was established under multiple constraints, with the objective of finding the shortest path while minimizing energy consumption. An improved A^* algorithm, combining weighted Euclidean and Chebyshev distances, was developed for solving the model. Results indicate that, compared to the traditional A^* algorithm, the improved version reduces solution time by 36.73%, providing more optimal paths. Altitude has a minor impact on total path length and duration but significantly affects UAV energy consumption. In high-altitude environments (3 500 m) compared to plain environments (630 m), UAV energy consumption increases by 48.00%. Wind speed and direction primarily influence energy consumption and total duration. At 3 500 m altitude and 8 m/s wind speed, flying with the wind reduces energy consumption by 64.74% and shortens duration by 41.01% compared to flying against the wind. A rise in atmospheric temperature near the fire to 40 ℃ has minimal effect on UAV path planning and energy consumption. These findings provide a theoretical basis for applying UAVs in path planning for plateau forest fire extinguishment.