  We investigate the effect of event-by-event fluctuations of the fireball
created in high energy nuclear collisions on hard probe observables. We show
that spatial inhomogeneities lead to changes in the nuclear suppression factor
of high momentum hadrons which can be absorbed in the quenching strength q.
This can increase the theoretical uncertainty on extracted values of q by up to
50%. We also investigate effects on azimuthal asymmetries v2 and dihadron
correlation functions. The latter show a promising residual signal of
event-by-event quenching that might allow us to estimate the size of spatial
inhomogeneities in the fireball from experimental data.
