This gives you a rough idea of what bands are open day and night. Data is based on the Sunspot Number, A and K indices and other indices. But this doesn’t take into account many factors like your location, the DX location, the characteristics of your station and the DX station. Just because 15m says Poor doesn’t mean you won’t hear anything on the band.
The areas noted in the forecast have the necessary atmospheric conditions to produce tropospheric bending of VHF, UHF and/or microwave radio waves. Tropospheric bending extends the range of radio & TV stations well beyond their normal limit and thus increases interference amongst stations as well. More Information HERE