This study investigates the effect of short-term storage under simulated climatic conditions on the storage-induced degradation of non-alloy steel metal-cored welding wires. Eight commercial wire grades were exposed for 48 h to four simulated climate conditions representing dry continental, wet continental, desert, and equatorial environments. The wires were evaluated using visual and stereoscopic observations, mass change measurements, relative electrical resistance testing, and multivariate statistical analysis. In equatorial conditions, surface degradation was detected for all wire grades, even after only 48 h of exposure. Dry climate conditions did not produce measurable mass increases, whereas storage in humid environments resulted in mass gains for all tested wires, with more pronounced changes at elevated temperatures. After 48 h under equatorial conditions, the metal-cored wires exhibited an average mass increase of 0.123%, reaching a maximum of 0.245%. Relative electrical resistance increased with the severity of the storage environment, reaching mean values of 3.71% after equatorial exposure and 2.62% after wet continental exposure, suggesting that this parameter can serve as a practical indicator of surface degradation. Cluster analysis identified three groups of wires with distinct degradation behavior, highlighting the variability within the metal-cored wire category and the need for careful evaluation before considering different wire grades as interchangeable consumables. The complex structure and product variability of stored metal-cored welding wires make visual inspection alone insufficient, while electrical resistance measurements combined with statistical classification may more reliably assess wire condition and support stable welding performance and consistent weld quality.