Word Learning Seasons: Climate Effects on Early Vocabulary in Monolingual and Bilingual Children

Children’s vocabularies reflect the dynamic worlds they inhabit, yet traditional models of language acquisition treat environmental influences as static. This study reveals how seasonal variations in weather systematically influence early vocabulary composition. Three studies involving 16–30 months old monolinguals and bilinguals (total N = 1294), examine how climate conditions affect word learning using parent-reported vocabulary checklists. Children in cold-weather regions (Wisconsin, Montreal) produced significantly more winter-related words compared to peers in milder climates (Texas, Florida), while seasonal analyses showed that within populations, winter word acquisition and knowledge peaked in the coldest months and declined during the warmest months. This pattern was most pronounced in older children, and in bilinguals with greater language exposure. Our research shows how children’s language systems adapt to environmental variations, advancing our understanding of language acquisition as a responsive process shaped by continuous interactions between cognitive development, language exposure, and the changing environmental landscape children navigate.