I was there one month ago... I can say I really got lucky!
This is pretty unexpected! This mind-blowing video shows the Iguazu Falls having a unusual and terrifying overflow on June 9, 2014.
The scary video records the terrifying moment floodwaters cover wooden footbridges hanging over the falls (on the Brazilian side) on which tourists usually walk. According to first measurements, there was 33 times more water than usual.
This unexpected flooding phenomenon started on Sunday during which the water flow rate rose from the usual 1,500 cubic meters per second to 5.230. On monday it had risen to amazing 46,300 cubic meters per second. Just compare the color of the water from this previous post.
Of course, officials closed the walks and people visiting the national park were only allowed to walk through the jungle and around the commercial sector. More pictures here.