Indicative ISO 9223 atmospheric-corrosivity class (C1 very low to CX extreme) and a 0-100 environmental-severity index for 42,138 power plants worldwide, computed per plant from its own coordinates (WorldClim temperature normals, Köppen-Geiger class, coast distance) via the ISO 9223:2012 informative method. For each plant: corrosivity class, severity index, dominant climate stressor (marine salt, thermal cycling, heat/UV, dust, humidity), annual/summer temperature, seasonal swing, coast distance and Köppen class. Purpose: durability / service-life context for OUTDOOR power-plant hardware — heat-recovery steam generators (HRSG), expansion joints, valves, flanges and their insulation. Indicative, model-based — NOT a site measurement or a condition assessment of any specific plant or operator; use as relative environmental-severity context. Methodology validated against Inzonex F3 HRSG field work (Persian-Gulf coast resolves to C5, matching the C5-M field anchor). Compiled from WRI GPPD, WorldClim, Köppen-Geiger and ISO 9223:2012. CC BY 4.0.