Australia, and many other countries are closed on Friday 19 April and Monday 22 April.
For the Easter break.
But, that's nothing, as I've posted before Japanese markets are closing for 10 consecutive days from April 27 to May 6, inclusive.
I've posted on this before, partially because of the fear of some sort of disruption in markets - flash crashes and what have you with Tokyo liquidity absent for so long. In total there are 6 trading sessions when markets in Japan are closed.
Pic via Bloomberg:
The 'sky is falling' folks are sweating on potential large moves in the diminished liquidity conditions. We should be so lucky. ;-)
For FX, yes, there will be an extension of the low liquidity period each morning when its only NZ and Australian forex markets open pre-Tokyo; this will last an hour or so longer than usual until Singapore and HK come in.