When we need to check what High frequency for Dxing at hourly. We can check data on Hourly Area Prediction or HAP. This data made by Australian Government in IPS radio and Space Services. example I need check in Bangkok to communication and see the color chart to see a recommended frequency for communication.
See at below for what Frequency for communicate.
http://www.ips.gov.au/Images/HF%20Systems/Global%20HF/HAP%20Charts/Bangkok.gif
