Space weather and band conditions

Rules behind the band ratings: 80m-40m: fair by day (D-layer absorption), good at night. 30m-20m: good by day; at night good from a solar flux of 120, fair from 80, else poor. 17m-15m: by day good from a solar flux of 110, fair from 80, else poor; at night fair from 150, else poor. 12m-10m: by day good from a solar flux of 150, fair from 110, else poor; at night fair from 200, else poor. A K-index of 4 lowers every night rating one step; 5 or more lowers every rating one step, and 7 or more two. An M-class X-ray flux lowers the day rating of 80m-40m and 30m-20m one step; X-class makes every day rating poor. Readings NOAA did not publish at the last fetch are null.