  Using the Polyakov--Nambu--Jona-Lasinio model the strange quark chiral phase
transition and the effect of its current mass on a hot magnetized three flavor
quark matter at zero chemical potential is investigated. The impact of the 't
Hooft mixing term on the restoration of the chiral symmetry on the light and
strange sectors is studied and the critical temperature dependence on the
magnetic field strength of the chiral strange transition is analyzed. It is
shown that the s quark is much less sensitive to the magnetic field than the
light quarks. Due to the 't Hooft term, it has a strong influence on the light
quarks at all temperatures for small magnetic fields and for temperatures close
to the transition temperature at zero magnetic field and above for strong
magnetic fields. In particular, the large mass of the s quark makes the chiral
transition of the light sector smoother and shifted to larger temperatures. A
scalar coupling that weakens when the magnetic field increases will originate
an inverse magnetic catalysis also in the s quark and smoothen the signature of
the crossover on thermodynamical quantities such as the sound velocities or the
specific heat.
