 The winter of 1939 – 1940 was exceptionally cold . One location on the Karelian Isthmus experienced a record low temperature of − 43 ° C ( − 45 ° F ) on 16 January 1940 . At the beginning of the war , only those Finnish soldiers who were in active service had uniforms and weapons . The rest had to make do with their own clothing , which for many soldiers was their normal winter clothing with semblance of an insignia added . Finnish soldiers were skilled in cross @-@ country skiing . 
