I used to think that only Mount Fuji was massive enough to have its own weather patterns, but 1,592-meter Mount Aso in Kyushu proved me wrong.
The clear skies and perfect late-September temperatures we were reveling in at the base of the hill dissipated quickly into mists and occasional thick cloud banks as we wound our way up the twisting western approach road to the summit of what is Japan's largest active volcano.
Even when the skies cleared, it was to reveal a constantly smoking plume snaking up from the Nakadake crater, reminding us that — benign as our day's adventure may seem — this towering mountain that dominates eastern Kumamoto Prefecture could erupt at any time.