GRASS GIS, a free and open source geographic information system, provides the functionality to manage, analyze and visualize geospatial data. Recently, support for managing the temporal dimension has been integrated into GRASS GIS as a response to an increasing accessibility and importance of spatio-temporal data. However, to fully benefit from such data new capabilities for exploratory visualizations are needed. We present a set of tools for spatio-temporal data visualization which reflects data complexity and also supports online sharing. The GRASS GIS Animation Tool is a desktop application working directly with different types of spatio-temporal data stored in GRASS GIS. We can display synchronized animations of raster, vector and 3D raster data in two- and three-dimensional views. To share spatio-temporal visualizations online, we have developed web map applications which enable users to explore the data as animations or derive supporting information such as histograms. Our solution does not require any server-site application and enables a file-based offline sharing and an easy online publication without any special requirements on users' software or servers. We demonstrate the desktop and online tools on several use cases, namely solar radiation and fire spread modeling, volumetric soil moisture analysis, and cumulative cost surface visualization.