Add PropagationStats to your ham radio site.
Radio blackouts are graded on a scale of R1 to R5 as follows:
Radio Blackouts Descriptor
Solar flux is a measurement of the intensity of solar radio emissions with a wavelength of 10.7 cm (a frequency of about 2800 MHz).
The value broadcast is in solar flux units that range from a theoretical minimum of about 50 to numbers larger than 300.
The A and K indices are a measurement of the behavior of the magnetic field in and around the earth.
The K index uses a scale from 0 to 9 to measure the change in the horizontal component of the geomagnetic field.