Abstract

Composite series of ENSO indices recorded over 36 months preceding major fire years in four National Parks in northern Patagonia were compared with series of these indices for individual years over the period 1950–1996 by means of an additive temporal phase coherence index. Logistic regressions of the dichotomous variable high vs low regional fire occurrence against the coherence index gained highest significant classificatory power using an index based on SST anomaly data between January of year –3 to August of year –1. Thus, warnings of extreme fire seasons could be declared as early as 3 months before the full fire season starts (i.e. early September). A regional fire season readiness index is proposed based on the periodicity of the Southern Oscillation, strong links with climate at particular regions of the globe, and empirically derived climatic controls on fine fuel buildup and coarse fuel desiccation. This long-range alerting tool could help decision-makers prepare preventative measures to mitigate the effects of large, high intensity wildfire seasons. However, it should be used with caution given that differences in timing in the onset of ENSO events and instability in teleconnection patterns could change climatic sequences, differentially affecting fire susceptibility.