Artificial spin ice arrays of micromagnetic islands are a means of
engineering additional energy scales and frustration into magnetic materials.
Despite much progress in elucidating the properties of such arrays, the `spins'
in the systems studied so far have no thermal dynamics as the kinetic
constraints are too high. Here we address this problem by using a material with
an ordering temperature near room temperature. By measuring the temperature
dependent magnetization in different principal directions, and comparing with
simulations of idealized statistical mechanical models, we confirm a dynamical
`pre-melting' of the artificial spin ice structure at a temperature well below
the intrinsic ordering temperature of the island material. We thus create a
spin ice array that has real thermal dynamics of the artificial spins over an
extended temperature range