‘The only noises in the frore air were of saws and axes and hammers.’
Now limited to dialect use, this is a variant of ‘frozen’ and can also be ‘froren’ or ‘frorn’. Perhaps just a necessary contraction in the frozen air.
Source: Henry Williamson, Tarka the Otter: His joyful water-life and death in the two rivers, illus. C.F. Tunnicliffe (Harmondsworth: Puffin Books, 1976 (1927)), p. 117