Understanding Solar Indices
- Understanding Solar Indices (ARRL pdf)
VOACAP (Voice of America Coverage Analysis Program) is free professional high-frequency (HF) propagation prediction software from NTIA/ITS, originally developed for Voice of America (VOA).
F2 MUF for selected skip distances
Great site with real time QSO/SWL information. Several options and overlays.
To get all options you need to register.