Vikings fought in snow as well, is there any historic info about how they fought?
Most snow scenes in the sagas are about fleeing or being chased across the snow, like in the Valla-Ljóts saga when a Viking jumps down a gorge, lands in snow drift above the ice and then slides all the way down to the bottom. Usually fights in wintertime are rare, but when they happened it normally occurred in or around a long house (where it can be assumed the snow may have been partially cleared). There's such a fight in the Svarfd?la saga.
However there are a few examples of Vikings fighting in snowy countryside. It is obvious that Viking men did not favour fighting in snow, since it either is so deep it hinders footwork or is packed down and slippery. As evidenced by this passage in the Vatnsd?la saga, "It is said that the very morning on which they were to go to the duel, there was such a thick fall of snow and a frost that not a soul ventured out"
But here are some rather painful examples of rare times they did...
Droplaugarsona saga: "He mounted the steep snowdrift, making for Helgi Droplaugarson, and thinking he had something against him. But when he came into the snowdrift, Helgi Droplaugarson aimed with a spear between his legs and pierced through the scrotum, and he fell backwards, and the spear stuck fast in the snowdrift, and he hung there on the snowdrift for the whole day."
Fóstbr?era saga: "When Butraldi was about halfway up, Thorgeir placed his spear underneath him, with the spearhead facing forwards, raised his axe to shoulder height and slid down the snow towards Butraldi. He heard the sound of Thorgeir whizzing down and looked up, but before he knew what was happening Thorgeir struck him full on the chest with his axe and cut right through him and he fell back down the slope."
Hope that helps...