  Lattice data for the QCD equation of state and the magnetic susceptibility
computed near the crossover transition at zero magnetic field are used to
determine the input parameters of a five dimensional Einstein-Maxwell-Dilaton
holographic model. Once the model parameters are fixed at zero magnetic field,
one can use this holographic construction to study the effects of a magnetic
field on the equilibrium and transport properties of the quark-gluon plasma. In
this paper we use this model to study the dependence of the crossover
temperature with an external magnetic field. Our results for the pressure of
the plasma and the crossover temperature are in quantitative agreement with
current lattice data for values of the magnetic field $0 \le eB \lesssim 0.3$
GeV$^2$, which is the relevant range for ultrarelativistic heavy ion collision
applications.
