Observe — what radio says about Earth
Every decoded WSPR path is a measurement of the ionosphere between two known points at a known minute. Thousands arrive each minute. Drawn on one world with the day/night line and NOAA's space-weather numbers, they become a slowly operating picture of the planet's radio weather. Replay scrubs the loaded window at 60×; click a station or an arc to tune the camera to it.
engine data as of 2026-08-31 · live lab feed · WSPR from wspr.live · Kp/F10.7 from NOAA SWPC
In plain English
Radio weather is real weather for anyone who depends on shortwave: the ionosphere rises and falls with the Sun, storms on the Sun shake it, and the day/night line sweeping around the globe changes which paths are open minute by minute. This page reads the public record of who heard whom, when and how well, and lays it over the world with the numbers that drive it. Nothing is modelled here — every arc is a report that actually happened.
What you'll see: A radio-weather layer that shows an ionospheric disturbance as it spreads, minutes before a forecast would, corroborated by more than one receiver — and a frozen, graded record proving it was early.
High above the clouds there is an invisible bouncy ceiling that radio waves bounce off. It changes all day: the Sun pumps it up, night lets it sag, and space storms make it wobbly. Thousands of tiny radios around the world say 'I heard you!' every couple of minutes. We draw every one of those hellos as a line on the map, so you can watch the ceiling work.One day you'll see the map ripple when the Sun sneezes — before the news knows.layers
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replay ×6002:16Z
DAYTWILIGHTNIGHTsun
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0 spots·0 rx stations active·0 bands open·kp — (—)·F10.7 —·window 1h·as of —
bands— (no spots loaded)
legendarc = one decoded WSPR path, colour = band, brightness = SNR, width = distancering beats = station decoded in the last 10 min (two rings ≥ 5)beacon ruler → our receiver, brightness = best SNR todayour receivertravelling dot = spot < 12 min old; arcs fade over 30 min; heat = rx activity, 90 s half-life
Ionosphere now
Kp
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F10.7
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sfu
No Kp reading yet. No F10.7 reading yet.
source NOAA SWPC
▸Learn more
Two numbers from NOAA drive most of what the map shows. Kp says how disturbed Earth's magnetic field is right now (updated every three hours); F10.7 says how active the Sun is (daily). The engine's Morlet programme found that the F10.7 level, not any rhythm in it, is what decides band behaviour.
Kp is a 0-to-9 storm score for Earth's magnet; F10.7 is how bright the Sun is in radio light. Calm magnet plus bright Sun means a strong bouncy ceiling.The engine's own rulers
WWV Fort Collins, CO · 908 km · 2.5/5/10/15/20 MHznot heard
WWVH Kekaha, Kauai, HI · 5,143 km · 2.5/5/10/15 MHznot heard
CHU Ottawa, ON · 2,713 km · 3.33/7.85/14.67 MHznot heard
▸Learn more
Time-signal stations at known distances (WWV in Colorado, WWVH in Hawaii, CHU in Ottawa) send a known carrier on a schedule. The Great Falls node measures each one hour by hour; the best hour's SNR today is shown. A beacon that vanishes by day and returns at night is the ionosphere, not the receiver. These are the arcs drawn in yellow on the map.
A radio lighthouse always sits in the same place saying the same thing, so we can use it like a ruler to measure the sky every day.RF weather — the bar
not yet: one receiver so far
An RF-weather layer would flag a cell of the sky whose radio behaviour is unusual for this hour. Before it exists it must clear all of this — and until it does, nothing here is called weather:
- · ≥ 2 independent receivers reading the same cells (today: 1 — the Great Falls node; pair an antenna and your node can be the second)
- · a baseline per (cell, hour) from ≥ 90 days of captures (day 5; testable 2026-11-25)
- · a z-score vs that baseline, frozen before the hour is read
- · corroboration with NWS radar (KGTF) so weather-of-the-air is never mistaken for weather-of-the-sky
▸Learn more
Anomalies are flagged, never promoted (doctrine #3). The WSPR arcs above are what the world heard; they are observations, not a forecast. The frozen, graded forecast lives on the FORECAST page.
We only get to shout 'storm!' once two different radios agree and we've written down what normal looks like first.▸What do these words mean?
WSPR — Weak Signal Propagation Reporter — thousands of hobby transmitters send a tiny, slow, timestamped signal on fixed frequencies, and every receiver that decodes one reports it to a shared public database. Each report is one proven radio path: who, from where, heard where, how strongly. We read that database, and our own receiver adds its reports to it.
SNR (signal-to-noise ratio) — How far a signal stands above the background hiss, in decibels. 0 dB means signal and noise are equal; each +10 dB is ten times the power. WSPR decodes down to about −30 dB — well below what an ear could hear.
Ionosphere — A layer of the upper atmosphere (about 60–1,000 km up) that sunlight turns into a weak electrical mirror. Shortwave radio bounces off it, which is why a signal from Montana can land in Japan. Its height and strength change with the Sun, the hour and the season.
F-layer — The highest and most important ionospheric layer (~150–500 km). It is what carries long-distance shortwave. By day it splits into F1 and F2; at night only F2 survives, and it is the F2 layer that decides how far a signal can reach after dark.
Solar terminator — The line on the globe separating day from night. The ionosphere changes fastest right along it, so signals that cross it — or run along it — often behave unusually for a short while around sunrise and sunset (the 'grey line').
Kp index — A 0–9 scale of how disturbed Earth's magnetic field is, published every three hours by NOAA. Kp 0–2 is quiet; Kp 5+ is a geomagnetic storm, which usually degrades high-latitude shortwave and can light the aurora.
F10.7 solar flux — The Sun's radio brightness at 10.7 cm wavelength, measured daily. It tracks solar activity well: high F10.7 means a more ionised ionosphere and higher usable frequencies. A level, not a rhythm.
Propagation — How a radio wave gets from transmitter to receiver: straight along the ground, bounced off the ionosphere, bent through the lower atmosphere, or scattered. The whole subject of this site.
Skip — A bounced path — the signal rises, reflects off the ionosphere and comes down far away. The ground between the transmitter and the first landing point hears nothing: the 'skip zone'.
Beacon — A transmitter that sends a known signal from a known place on a schedule, so anyone can use it as a ruler. WWV (Colorado), WWVH (Hawaii) and CHU (Ottawa) are time-signal stations we use exactly this way.
Maidenhead grid — The Maidenhead locator: the world cut into squares named with letters and numbers (DN47 is the square that holds Great Falls). Radio amateurs report locations this way, so every WSPR report already carries a rough position.
dB (decibel) — The decibel, a logarithmic unit for comparing power. +3 dB is double, +10 dB is ten times, +20 dB is a hundred times. Radio uses it because signals span an enormous range.