Solar-rich but water-scarce regions face a fundamental challenge in producing green hydrogen because conventional electrolysis depends on reliable freshwater supplies. This study investigates a fully self-sustained offgrid solar powered system that integrates atmospheric water generation and water electrolysis to enable hydrogen production under severe water limitations. Using Jordan as a case study, ten bioclimatic zones were analyzed, ranging from sub humid Mediterranean highlands to arid Saharan deserts. A dynamic hourly simulation was conducted using a standardized 20 kW solar array and atmospheric moisture as the sole water source. Results show that climate strongly affects both water harvesting and hydrogen output. Sub humid and semi-arid Mediterranean regions such as Tafila and the Dead Sea achieved the lowest levelized hydrogen costs at 8.22 and 8.28 $/kg. In contrast, arid Saharan regions such as Ma'an recorded the highest cost at 11.50 $/kg. A twoparameter climatic sweep identified conservative feasibility thresholds near a minimum irradiance of 450 W/ m2 and a minimum relative humidity of 37 %. Hydrogen price sensitivity further showed that most regions reach break-even at selling prices between 6.73 and 7.54 $/kg H2. These findings demonstrate that pairing solar energy with atmospheric water harvesting enables a viable pathway for sustainable hydrogen production in arid and semi-arid climates.