What these alerts actually are
NOAA's Space Weather Prediction Center issues a continuous stream of short text products whenever specific, predefined thresholds are crossed in the data it monitors. Unlike the Kp index or the aurora oval map, which update on a fixed schedule regardless of conditions, these alerts are event-driven -- they only appear when something has actually happened or is judged imminent. This page shows the subset of that feed relevant to geomagnetic activity and the aurora specifically, filtered from the full space weather alert catalogue, which also covers solar radiation storms and radio blackouts that mostly matter for satellite operators and aviation rather than aurora viewing.
Reading the message types
Each alert falls into one of a handful of categories. A watch is the earliest warning, issued when NOAA judges conditions capable of producing a storm are likely in the coming day or days -- typically triggered by an Earth-directed coronal mass ejection or a persistent coronal hole stream being observed on the Sun. A warning follows when real-time data shows a storm is imminent or has just begun. An alertmarks the moment a specific numeric threshold -- a Kp value, a G-scale level -- has actually been reached, and a summary typically closes out a period, reporting the highest level reached. None of these replace the live Kp index or aurora oval map above them on this site; they are complementary event markers layered on top of the same underlying data.
The G, R and S scales
NOAA communicates severity through three parallel scales, each running 1 (minor) to 5 (extreme): G for geomagnetic storms, which is what drives the aurora and the scale most relevant here; R for radio blackouts, caused by solar flares disturbing the ionosphere and mainly a concern for high-frequency radio and aviation communications; and S for solar radiation storms, energetic particle events that matter most for satellite health, polar flight routes and crewed spaceflight. An alert's scale code (for example G2 or R1) tells you immediately which of these three domains it belongs to and how severe NOAA judges it, without needing to parse the full message. See the NOAA G-scale explained for a full breakdown of what each geomagnetic level means in practice for aurora visibility.
Why the list is often empty
Most of the time, particularly outside an active storm, this list will be empty or show only an older summary -- that is the normal, quiet-conditions state, not a sign of a broken feed. Space weather is genuinely episodic: real geomagnetic storms capable of producing widely visible aurora happen on the order of days per month even during an active phase of the solar cycle, not continuously. For a sense of where the current solar cycle sits and what that means for how often storms should be expected, seesolar cycle 25/26 explained. If you want a forecast that already accounts for how rare or common activity currently is at your specific location, the personal verdict page folds this alert feed together with the Kp index, live aurora oval data, darkness and moon phase into one answer.
Frequently asked questions
What is the difference between a watch, a warning, and an alert?
A watch is issued ahead of time when conditions capable of producing a storm are expected (for example, an Earth-directed CME has been observed). A warning is issued when a storm is imminent or just beginning, based on real-time data. An alert (and its close relative, a summary) reports that a specific threshold has actually been reached or that a period has now ended.
What do the G, R and S letters in a scale mean?
They are NOAA's three space weather scales: G for geomagnetic storms (which drive aurora), R for radio blackouts (caused by solar flares affecting the ionosphere), and S for solar radiation storms (energetic particles, mainly a concern for satellites, high-altitude flights and astronauts). This page focuses on G-scale and aurora-relevant K-index alerts, since those are what matter for visible aurora.
No alerts are showing -- does that mean something is broken?
No. An empty list is the normal, quiet-conditions state and is shown as such, not as an error. NOAA only issues these products when a specific condition is met; most of the time, especially outside a storm, there is nothing to report.
How quickly do alerts appear here after NOAA issues them?
Within roughly a minute -- this page polls NOAA's alerts feed on the same cadence as the rest of the site's live data. The timestamp on each alert is when NOAA issued it, not when this page happened to load.