As was hopefully explained during your studies to become a radio amateur, HF (3-30MHz) relies on signals being bounced off the Ionosphere – and the state of the Ionosphere determines which bands will work best, and how far signals are likely to travel.
Two common questions – how do I know what bands are “open”, and how can I make predictions on propagation? We’ll do our best to answer those here:
How can I tell what bands are open?
As you travel around the web, you’re bound to come across graphics like the following – most of these come from a chap called Paul N0NBH who makes these available for any website (see: how to add to your own site). This graphic show genuine data on the state of the various HF bands now – Good, Fair or Poor
Another easy-to-use site is solar.w5mmw.net which also gives the state of the various bands
Real-time Data
Whilst the “band state” indicators above are useful, a top tip is to see what signals are being sent from the UK in real-time, and how far they’re getting. For this, it’s worth playing with the website PSKReporter.
The map page is key, and at the top, you’ll notice various menus. The trick is to set this to “Signals sent from the UK on all bands in the last 15 minutes. The resulting map will show where signals on all bands are currently reaching – so if you want to make contact with a specific country, you can see what band others have just used to make a contact.
This link opens the map in the right configuration: 
