Exactly the same occurred in October 2013 when a row of rain clouds rapidly developed over Izu Oshima Island, south of Tokyo, tipping 500mm of rain in a six-hour period, triggering landslides and leaving 36 people dead.
Freak waves were also a possibility, generated as ocean swells collide with each other.
In October 2002, an unexpectedly high wave hit a breakwater in Atami in central Japan, knocking over 17 people, mainly anglers, and two died.
Given the unpredictability of Hagibis' path and strength, the only logical move was to cancel the New Zealand and Italy match in Toyota, and the game between England and France in Yokohama. Under RWC rules, those games are recorded as 0-0 draws.
After all, what's a rugby game when lives are on the line?