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KJ5MLB · Henryetta, Oklahoma

Space Weather & Band Conditions

Real-time solar data for amateur radio operators

HF Propagation

Band Conditions

How good are the HF bands right now? Conditions vary between day and night — use the toggle to switch views. Good means reliable contacts over long distances. Fair means usable but inconsistent. Poor means high noise or signal absorption. Please note you need to toggle between day or night conditions (this is not automatic.)

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Solar Activity

Solar Conditions

These numbers describe the current state of the sun and Earth’s magnetic environment. Each one affects radio propagation in different ways — hover over any card to learn more, or see the explainer at the bottom of the page.

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Day / Night Terminator

Sunlit Earth Map

This map shows which parts of the Earth are currently in daylight and which are in darkness. The boundary between them — called the terminator — is where propagation conditions change most dramatically. The dark shaded area is in night, which generally favors lower HF bands like 80m and 40m.

Sunrise
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Henryetta, OK
Solar Noon
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Sun at highest point
Sunset
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Henryetta, OK
Daylight
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Hours of sunlight today
Sun Status
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Current condition

Live day/night terminator · Updates every 30 seconds · Built with Leaflet + Leaflet.Terminator

VHF & Above

VHF & E-Skip Propagation

Unlike HF bands, VHF signals normally travel only line-of-sight distances. However, special atmospheric conditions can sometimes allow VHF signals to travel hundreds or thousands of miles. E-Skip (sporadic-E) is the most common of these and can open 6m and 10m to distant contacts unexpectedly.

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Learn More

Understanding Space Weather

New to ham radio propagation? Here’s a plain-English guide to what these numbers actually mean.

What do these numbers mean? Click to expand
Solar Flux (SFI)
A measure of how active the sun is at radio frequencies. Higher is better for HF. Below 70 = poor conditions. 70–100 = fair. 100–150 = good. Above 150 = excellent. The sun updates this number roughly every hour.
Sunspot Number (SN)
Counts the visible dark spots on the sun’s surface. More sunspots generally means higher solar flux and better HF propagation. We’re currently near the peak of Solar Cycle 25, which is why conditions have been favorable.
K-Index
Measures disturbances in Earth’s magnetic field over the last 3 hours. Runs from 0–9. Lower is better for radio. 0–1 = quiet and calm. 2–3 = unsettled but workable. 4 = active, some degradation. 5+ = geomagnetic storm, significant HF disruption especially at high latitudes.
A-Index
A daily average of geomagnetic activity — think of it as the K-Index smoothed out over 24 hours. Below 10 = calm. 10–29 = unsettled. 30–49 = active. 50+ = storm conditions. Useful for planning skeds in advance.
Solar Wind
The continuous stream of charged particles flowing from the sun. Measured in km/s. Typical speed is 300–500 km/s. Higher speeds (especially above 500 km/s) can compress Earth’s magnetic field and increase the K-Index, degrading HF propagation.
Geomagnetic Storm
A major disturbance of Earth’s magnetosphere caused by intense solar activity. Ranges from Quiet to Extreme (G1–G5 scale). Even a minor storm (G1) can degrade HF signals at higher latitudes. A severe storm (G4–G5) can disrupt HF communication globally and is also when aurora is visible further south.
E-Skip
Sporadic-E propagation — an unpredictable but exciting phenomenon where the E-layer of the ionosphere becomes highly ionized in patches, allowing VHF signals (especially 6m and 10m) to travel 500–2000 miles. It happens most often in late spring and early summer, and can open a “dead” band with no warning.
Day vs. Night
Solar radiation ionizes the upper atmosphere during the day, which actually absorbs lower frequency signals (80m, 40m). At night, that absorption layer fades and lower bands come alive — you can often work stations thousands of miles away on 40m after dark that you couldn’t hear at noon.

Data provided by HamQSL.com / N0NBH, sourced from NOAA Space Weather Prediction Center. Data updates every 15 minutes. For real-time alerts, visit NOAA SWPC Alerts.