Interpreting Solar DataA Index: 1-6 (best), 7-9 (fair), 11+ (bad) - A Index represents the overall geomagnetic condition of the ionosphere over a given 24 hour period.
K Index: 0 or 1 (best), 2 (ok), 3+ (bad), 5 (very bad) - K Index is the overall geomagnetic condition of the ionosphere averaged over the planet over the past 3 hours. K index indicates geomagetic storms. Below 10 MHz, a K Index of 5+ increases noise level appreciably, a K index of 7+ degrades HF significantly.
SFI: 70 (not good), 80 (good), 90 (better), 100+ (best) - SFI is the Solar Flux Index and is a measure of total radio emissions from the sun. Higher Solar Flux generally suggests better propagation on the 10, 12, 15, 17, & 20 Metre Bands. Solar Flux rarely affects the 30, 40, 60, 80, & 160 Metre bands. Generally, propagation conditions are best when the A index is 10 or lower and the K index is 3 or lower.
X-Ray: Solar X-Ray emissions will cause shortwave fadeout. They are classified from weak to strong as A, B, C, M or X