Before you begin: No SDR setup needed to read the conditions. Use a receiver to check what can actually be heard.
Current Solar Weather and Estimated Band Outlook
Solar Weather & Band Outlook
Live clock · conditions timestamps below show when each source was updated.
Solar Activity SFI Solar flux / SFISolar radio emission at 10.7 cm, reported in solar flux units (sfu). It is an indicator of solar activity, not signal strength at your antenna.Reading the rangeSFI is a measured value, not a fixed 0–9 scale. Values are often roughly 60 to several hundred over a solar cycle; these are approximate context, not band-opening thresholds.At your stationHigher flux generally supports higher HF frequencies. Check the band outlook and actual reception; there is no single value that guarantees 10 m or 15 m is open.Click or tap ? to keep open. Escape or click outside to close.
—Higher solar flux generally supports higher HF frequencies. It does not guarantee an opening.
Waiting for NOAA dataK Index Planetary Kp · magnetic disturbance Planetary KpK describes disturbance at one magnetic observing station. Kp combines observations into a planetary estimate over a three-hour interval. This panel shows Kp, on the 0–9 scale.Reading the rangeBelow 5: below NOAA’s geomagnetic-storm threshold. 5–9: storm-level activity, with increasing severity. Below 5 does not guarantee good propagation.At your stationHigher disturbance can disrupt HF paths, particularly toward high latitudes. Compare more than one band before assuming a receiver fault.Click or tap ? to keep open. Escape or click outside to close.
—Lower means less geomagnetic disturbance. Kp 5 or above indicates storm-level activity.
Waiting for NOAA dataHF Blackout Status R scale HF radio-blackout scaleNOAA’s R scale describes solar-flare radio-blackout severity, mainly affecting the sunlit side of Earth.Reading the rangeR0: none reported here. R1: minor. R2: moderate. R3: strong. R4: severe. R5: extreme.At your stationNo reported event does not guarantee an open path. During a reported event, check NOAA’s HF absorption map and compare reception on another band.Click or tap ? to keep open. Escape or click outside to close.
—Solar-flare effects can weaken or interrupt HF on the sunlit side of Earth.
Waiting for NOAA dataEstimated HF Outlook Estimated HF band outlookCalculated Good, Fair, and Poor guidance for broad HF band groups. Daytime and nighttime refer to illumination along the radio path.Reading the rangeGood: relatively favorable. Fair: mixed or variable. Poor: more challenging. These are qualitative ratings, not measured probabilities or an open/closed switch.At your stationChoose a band to investigate, tune a real signal, and check audio readability or decoding. Local noise, antennas, mode, season, and the path still matter.Click or tap ? to keep open. Escape or click outside to close.
| Bands | Daytime | Nighttime |
|---|---|---|
| 80–40 m | — | — |
| 30–20 m | — | — |
| 17–15 m | — | — |
| 12–10 m | — | — |
Good: worth checking · Fair: variable · Poor: more challenging. These broad ratings do not declare a band open or closed.
Not rated here: 160 m, 60 m, and VHF/UHF. These are broad estimates, not measured local band conditions.
Waiting for band-outlook dataLoading conditions…
General outlook, not local reception or a path-specific forecast. Day and night depend on the locations along the path. Sources: NOAA SWPC · N0NBH / HamQSL.
Recent Kp History
Compare recent NOAA estimated three-hour planetary Kp readings. This is observed geomagnetic context, not a forecast of your station’s reception. The newest interval may still be developing and can be revised.
Loading recent Kp readings…
Read the Kp Values and UTC Intervals
| Interval Start (UTC) | Interval End (UTC) | Estimated Kp |
|---|
The chart uses a fixed 0–9 scale. The dashed line marks Kp 5, the geomagnetic-storm threshold; a lower value does not guarantee an opening. Missing intervals are left blank. Source timestamps describe the intervals, not when this website last refreshed.
Forecast and HF Absorption Map
NOAA 3-Day Forecast ↗ — use the forecast sections to plan ahead; read its issue time and distinguish predictions from recently observed conditions.
NOAA HF Absorption Map (D-RAP) ↗ — inspect the geographic extent of modeled absorption when investigating broad HF degradation. The map is guidance, not a measurement of your particular station-to-station path.
At the radio, compare what the outlook suggests with actual signal readability on two or three bands. Keep local noise, antenna performance and receiver settings in the investigation.
What the Readings Tell You
- Solar flux / SFI
- A measure of solar radio emission at 10.7 cm. It is used as an indicator of solar activity relevant to ionospheric propagation; it is not a receiver signal-strength reading.
- K index and planetary Kp
- A local K index describes geomagnetic disturbance at one observing station. Kp combines observations into a planetary index; NOAA’s feed supplies the estimated Kp shown here. The scale is 0–9 over a three-hour interval. Higher values indicate greater disturbance, which can change HF propagation, particularly on high-latitude paths.
- Radio blackout / R scale
- NOAA’s R0–R5 display here reports the current radio-blackout scale. R0 means no event reported on this scale; it does not mean every HF path is usable. Solar-flare effects particularly affect the sunlit side of Earth.
- Day / night band outlook
- N0NBH / HamQSL calculates broad Good, Fair, or Poor ratings for grouped HF bands. These are general estimates, not location-specific predictions. Both columns are shown because daylight conditions differ along an actual radio path.
The grouped 80–40 m rating does not separately assess each band. The table does not cover 160 m, 60 m, or VHF/UHF. No rating is inferred for those bands.
A Practical Reading Order
- Check the timestamps. An old reading is background, not a current condition report.
- Check blackout status and Kp. A reported blackout or geomagnetic storm may help explain broad changes in reception. Kp 5 is NOAA’s geomagnetic-storm threshold; Kp below 5 does not guarantee good reception.
- Use solar flux as context. Higher SFI generally supports higher HF frequencies, but season, time, path, antenna, and geomagnetic conditions still matter. There is no single SFI number that guarantees a band opening.
- Check a band, then listen. Pick the day/night column relevant to the path. Investigate a promising band, but try a second one rather than treating a Poor rating as closed.
We keep three measurements because they answer different questions: solar activity, geomagnetic disturbance, and current solar-flare blackout status. Sunspot number overlaps with SFI as solar-cycle context; solar wind, Bz, and particle flux are useful for deeper study but are not needed for a first operating check. This page does not estimate your local S-meter noise floor.
Solar Image Reference
NASA/SDO AIA 193 Å image, saved 20 Oct 2026; illustrative, not a live feed. Original source ↗
Use the Outlook with Your SDR
- Note UTC, the source timestamps, and any disturbance or blackout indication.
- Choose two or three bands your receiver and antenna support. Look for actual activity rather than assuming that a rating guarantees contacts.
- Keep receiver gain and waterfall display settings consistent when comparing observations. A change in display color alone is not a propagation change.
- Tune a signal, select the correct mode and receive filter, and check audio readability or decoding.
- Record the band, UTC, antenna, and what you heard. Compare another band or receiving antenna before changing the station configuration.
Practice reading the SDR screens ↗ · Compare signal-to-noise difference ↗
Predicted Conditions and Observed Activity
An apparently empty waterfall can result from antenna performance, local noise, mode or receiver settings, propagation, or a lack of transmitters. A global Poor rating does not establish that your particular path is closed; a Good rating does not guarantee a contact.
This panel shows solar measurements and a calculated outlook. It does not contain live reception reports from W3UJ or a live spot network. NOAA’s Radio Communications Dashboard also provides an HF absorption map for investigating possible solar-related degradation.
Sources, Update Times, and Unavailable Data
Measurements come from NOAA SWPC; the estimated HF outlook comes from N0NBH / HamQSL. Each measurement retains its own source timestamp in UTC. Retrieved time records when this site obtained the feed, not when an observation was made.
Shared responses are cached for up to five minutes. Open pages refresh every ten minutes and when you return to the tab. Readings are flagged stale after 72 hours for solar flux, six hours for Kp, two hours for blackout status, and three hours for the band outlook. These are this site’s freshness limits, not NOAA alert thresholds.
If a feed fails, its value is shown as unavailable. Stale values remain labeled and band-rating colors are removed. No sample values are substituted for live data.
Further Learning
- W5MMW: solar conditions and propagation readings
- KV5R: solar activity and propagation background
- W5NOR / SCARS: solar-weather resources
- NOAA: the planetary K-index
These pages were reviewed for layout and educational ideas. Our live measurements continue to come directly from NOAA, with the broad HF outlook credited to N0NBH / HamQSL.
Where next: Use the outlook during a listening session →
Solar measurements and estimated outlook are supplied by the live sources identified above; the SDR operating method is a W3UJ guide. Sources and editorial scope.