The story
From fore- + winter. Cognate with Saterland Frisian Fóarwinter (“forewinter”), West Frisian foarwinter (“forewinter”), Dutch voorwinter (“forewinter”), German Vorwinter (“forewinter”), Danish forvinter (“forewinter”), Swedish förvinter (“forewinter”), Icelandic forvetur (“forewinter”).
Etymology from Wiktionary, CC BY-SA 4.0.