HF propagation map
An excellent online HF propagation is MUF 3000 Km Map that can be used to predict ham bands' conditions.
1. How to use this HF propagation map 2. Additional notes 3. Animated map
Read more about HF propagation map. See also an index of terms for HF Radio Propagarion.
The project "Understanding HF Propagation" provides a detailed overview and tutorials on HF propagation.