How to Understand NOAA Space Weather Alerts
NOAA's Space Weather Prediction Center uses a tiered system familiar to anyone who has seen a hurricane bulletin: watch, warning, and alert. Each tier represents a different level of certainty and timeframe.
Watch, Warning, Alert
A watch means storm-level conditions are possible in the next 1–3 days. A warning means conditions are expected within the next few hours. An alert means the threshold has actually been crossed right now. Watches give you time to plan; alerts tell you to look up.
R, S, and G Categories
Every alert is tagged R (radio blackout from flares), S (solar radiation storm from energetic particles), or G (geomagnetic storm from CMEs and high-speed streams). Each runs 1 through 5. An R2 warning matters to HF radio operators; a G3 warning matters to aurora chasers and grid operators.
How to Subscribe
NOAA publishes alerts as an RSS feed, an email list, and a public JSON API. Most aurora apps and dashboards pull from that API, so the alerts you see in third-party tools are the same ones the government issues.
Frequently Asked Questions
Does a G1 warning mean I'll see aurora?
From high latitudes (northern Scandinavia, Alaska, northern Canada), usually yes. From mid-latitudes, G3 or higher is more likely to produce a visible display.
Are alerts free?
Yes. NOAA SWPC alerts and data are U.S. government-funded and released without restriction.