This study investigates the accumulation of toxic heavy metals (HMs)-cadmium (Cd), chromium (Cr), cobalt (Co), nickel (Ni), lead (Pb), and strontium (Sr)-in potato tubers grown under diverse meteorological and soil conditions in Central-Eastern Poland. Conducted from 2021 to 2023 at the Variety Assessment Experimental Station in Uhnin on light acidic soil, the field experiment employed a randomized block design with three replications. Forty potato cultivars of varying maturity were evaluated, with agronomic practices adhering to GAP and uniform fertilization applied. Potato tubers were exposed to thermal neutron flux for 2 h. Gamma radiation detection was conducted using a high-purity germanium (HPGe) detector cooled with liquid nitrogen to enhance resolution. The study highlights significant phenotypic variability in HM accumulation, influenced by genetic, environmental, and genotype × environment interaction factors. Results showed substantial effects of cultivar, year, and their interactions, with varieties (V) accounting for 8.7%-36.2% of the variance, environmental factors (Y) contributing 41.2%-82.2%, and genotype × environment interactions (V × Y) ranging from 5.5% to 46.7%. Year-to-year variability was most pronounced for lead, whereas nickel showed the least variability. Soil pH and humus played a key role in shaping the bioavailability and accumulation of metals in potato tubers.