  The current paper is devoted to the study of spreading speeds and transition
fronts of lattice KPP equations in time heterogeneous media. We first prove the
existence, uniqueness, and stability of spatially homogeneous entire positive
solutions. Next, we establish lower and upper bounds of the (generalized)
spreading speed intervals. Then, by constructing appropriate sub-solutions and
super-solutions, we show the existence and continuity of transition fronts with
given front position functions. Also, we prove the existence of some kind of
critical front.
