The project was originally formed in 1994 to "push the limits" of black metal music, where the vocals are mostly clean sung, and only a few parts per song that had the traditional screaming vocals. The sound of Vintersorg has vastly changed over the years, as their earlier sound had more of a folk influence, and later on, more of an experimental sound. This transformation was most notably marked with the release of the Cosmic Genesis album, and the change in sound progressed from album to album, with the 2004 album The Focusing Blur being an extremely avant-garde album. The band's vocal elements have changed from album to album as well, starting out with low-pitched, powerful baritone singing, and gradually shifting towards softer, higher-pitched delivery with more use of harmony and layering with black metal vocals. Solens rötter, marked a return to the earlier folk metal style, while retaining the more complex and non-traditional guitar arrangements and song structures of later albums. On Jordpuls and Orkan there was a continuation with the Swedish sung material and nature oriented themes.
Along with this change in musical style, the lyrical topics began to shift as well. On earlier albums, the lyrics are all written and performed in Swedish, and dealt with topics of nature and paganism. With the advent of Cosmic Genesis, the lyrics were now written and sung mostly in English, and now dealt with scientific ideas such as astronomy and cosmology, philosophies such as metaphysics, and other ideas such as astrology. In the Cosmic Genesis booklet, Vintersorg extends thanks to Dr. Carl Sagan, author of the book Cosmos. Since, then, the band has alternated between both English and Swedish lyrics, sometimes using both on the same album. In keeping with the band's return to its folk roots, the latter albums are also sung entirely in Swedish and deal with more traditional themes.