At a glance
| Band | Best time | Typical use |
|---|---|---|
| 160 m | Night, around dawn and dusk | Winter DX, strong in the gray line |
| 80 m | Night | Regional by day (NVIS), DX at night |
| 60 m | Night, some day | Mostly regional, steady |
| 40 m | Night, all-round | The only low band that works day and night |
| 30 m | All day, evening | Digital and CW DX, steady in any cycle |
| 20 m | Daylight into the evening | The classic DX band |
| 17 m | Daylight | Quiet DX band, good in moderate flux |
| 15 m | Daylight | DX when SFI is above about 100 |
| 12 m | Daylight | DX at higher solar flux |
| 10 m | Daylight | Open at high flux; local and Es otherwise |
Why the pattern exists
By day, the D layer absorbs the low bands, so 160 and 80 metres work only over short distances, while the highly ionised F layer supports the high bands. After sunset the D layer vanishes, absorption drops, and the low bands carry DX. Meanwhile the F layer loses ionisation and the high bands close. The bands between, such as 40, 30 and 20 metres, bridge the two regimes.
How the solar cycle changes the picture
At solar maximum, 15, 12 and 10 metres can stay open into the evening and 20 metres may be busy all night. At solar minimum, 20 metres closes early and the lower bands carry most of the traffic. Check the live estimate for every band on the HF band conditions page or experiment with the what-if simulator.
Keep reading
What Is HF Propagation?HF propagation explained for radio amateurs: how the ionosphere bends 3-30 MHz signals, why bands open and close, and what MUF and skip distance mean.Gray Line Propagation for DXWhat the gray line (day/night terminator) is, why signals travel unusually well along it at dawn and dusk, and how to time DX contacts on the low bands.Solar Flux Index (SFI) ExplainedWhat the 10.7 cm solar flux index (SFI, F10.7) is, how it is measured, and which SFI values open 20, 15, 12 and 10 metres for radio amateurs.
