HF Band Conditions — 80m, 40m, 20m, 15m, 10m, 6m Day vs Night

HF Band Conditions — 80m, 40m, 20m, 15m, 10m, 6m Day vs NightA guide to each amateur radio HF band — what makes it open or closed, day/night behavior, sensitivity to solar flux and geomagnetic activity. How the BloomWX condition table is computed.The HF bands behave very differently from each other and very differently between day and night. The Ham Shack condition table collapses today's SFI and K-index into a Day / Night verdict for each band.The bands

80m (3.5 MHz): Night band. D-region absorption kills it during day.

40m (7 MHz): Day-and-night workhorse. Long DX at night, regional during day.

30m (10 MHz): WARC band, CW/digital only.

20m (14 MHz): The DX workhorse. Open globally during day at most SFI.

17m (18 MHz): WARC band. Behaves like 20m but quieter.

15m (21 MHz): Day band, opens at SFI >= ~100.

12m (24 MHz): WARC band. Opens at SFI >= 110.

10m (28 MHz): Day band, magic band. Needs SFI >= 100+ for daytime F2.

6m (50 MHz): Borderline HF/VHF. Sporadic-E openings (May-July) most common.

Verdicts: Closed, Poor, Fair, Good, Excellent.Part of the BloomWX learn library — beginner-friendly explainers covering every surface of the BloomWX weather dashboard. Open BloomWX to see live data for any U.S. county.