The distribution of avalanche runout varies in space and time for individual avalanche paths and from mountain range to mountain range. In this paper, such variations are considered based on the assumption (supported by data worldwide) that the spatial distribution of extreme avalanche runout follows a Gumbel distribution and that the arrival rate of avalanches can be modelled as a Poisson process. The input required is a set of extreme avalanche runout distances for the mountain range and a knowledge of avalanche frequency at the beginning of the runout zone for the path in question. Such information allows theoretical estimation of the effective return period as a function of position, which is very important in zoning applications. In addition, general expressions are derived to relate Gumbel parameters for different mountain ranges to a frequency index to explore general frequency implications from one mountain range to another. The estimated Gumbel parameters imply consistent relationships for expected avalanche frequency and terrain from one mountain range to another.Key words: snow avalanches, runout distances, return period, frequency, terrain.