Activity on the Sun has a major impact on ionospheric radio propagation. It affects a variety of forms of HF radio communications, including two-way radio communications, maritime mobile radio communications, radio broadcasting, and amateur radio communications. Knowing the Solar Flux Index and K Index will help you determine current conditions and know what to expect in the near future. There are dozens of sites on the web that provide this data.
For Best Conditions:
- Solar Flux should remain above 150 for a few days (scale from 0-300)
- K Index – should be below 2
- A Index – 5 or more indicates a geomagnetic storm (scale from 0-9)
Citation: Who Stole My Bands? A Look at Ham Radio and the Capricious Sun – Mark Haverstock K8MSH