EUSO-SPB1 was a balloon-borne mission of the JEM-EUSO (Joint Experiment Missions for Extreme Universe Space Observatory) Program aiming at the observation of UHECRs from space. The EUSO-SPB1 telescope was a fluorescence detector with a 1 m2 Fresnel refractive optics and a focal surface covered with 36 multi-anode photomultiplier tubes for a total of 2304 channels covering ~11 degrees FOV. Each channel performed the photon counting every 2.5 µs time frame, allowing for spatiotemporal imaging of the air shower events. Being provided with an active trigger algorithm, EUSO-SPB1 was the first balloon-borne experiment having a potential to detect air shower events initiated by cosmic rays in the range of several EeV. On 25 April 2017, EUSO-SPB1 was launched from Wanaka, New Zealand on the NASA’s Super Pressure Balloon that flew at ∼ 16 − 33 km flight altitude for ~292 hours. Before the flight was terminated due to an unexpected gas leakage, we retrieved the ~27 hours data acquired in the air shower detection mode. In the present work, we aim at evaluating the role of the clouds during the operation of EUSO-SPB1. We employ the WRF (Weather Research and Forecasting) model to numerically calculate the cloud distribution in the EUSO-SPB1 FOV. We discuss the keys result of the WRF model and the impact of the clouds on the air shower measurement and on the efficiency of the cosmic ray observation. We will also mention the relevant issues towards future ballon-borne and satellite-based UHECR observation missions.