I use VOAProp http://www.g4ilo.com/voaprop.html
which runs on WIN98 or later and on Linux under WINE.
From the web site:
VOAProp was written to meet my need for a program that would show me what HF band propagation should be like on a particular day on a particular band. It is the successor to my popular propagation program HFProp, which used fast, but not very accurate propagation modelling algorithms. VOAProp uses the well-regarded VOACAP forecasting software, and provides a simplified graphical interface for it so that you can get an overall idea of how propagation should be at a given time and date without getting bogged down in detail.