Industrial machinery fleets play a critical role in Rwanda's economic development, particularly in sectors such as agriculture, manufacturing, and construction. A quasi-experimental design was employed, incorporating surveys and operational data from selected industrial enterprises in Rwanda. Statistical analysis included regression models to assess the impact of environmental factors on machinery reliability. The statistical model revealed a significant positive correlation (r = 0.75) between ambient temperature and machinery failure rates, indicating that higher temperatures lead to increased failures within the fleet. This study highlights the importance of monitoring environmental conditions for maintaining industrial machinery fleets' reliability in Rwanda's diverse industrial landscape. Industrial operators should implement preventive maintenance strategies based on weather patterns to optimise machinery performance and reduce downtime. Quasi-Experimental Design, Industrial Machinery Reliability, Environmental Factors, Regression Analysis