PCRaster is a collection of tools and software libraries tailored to the construction of spatio-temporal environmental models. Application domains are amongst others hydrology (rainfall-runoff, global water balance, groundwater (with Modflow)), ecology, or land use change. PCRaster includes a rich set of spatial operations for manipulating and analysing raster maps. A Python framework supports Monte Carlo simulations and data assimilation (Ensemble Kalman Filter and Particle Filter). The Aguila tool allows for the interactive visualisation of stochastic spatio- temporal data.