The number of snow avalanche cycles occurring in Iceland is correlated to a major source of variability in climate, the North Atlantic Oscillation. A new index for this oscillation is produced that reflects the cumulative effect of snow build-up in a starting zone. An analysis of the time-series for this index shows that recent avalanche tragedies in Iceland are linked to a rise in this index. Consequently, estimations of avalanche return periods and thus, avalanche hazard zones, may need re-evaluation. Because the oscillation has an impact upon climate throughout the Northern Hemisphere, this may be necessary in a number of other countries.