How Aurora Forecast USA Works

Aurora Forecast USA delivers real-time northern lights predictions tailored specifically to the United States. Our system monitors space weather and local atmospheric conditions around the clock, updating every 15 minutes so you always have the most current aurora outlook for your location.

Data Sources

NOAA Space Weather Prediction Center (SWPC)

Our primary space weather data comes directly from NOAA's Space Weather Prediction Center, the US government's official source for solar and geomagnetic activity. We ingest real-time measurements of solar wind speed, interplanetary magnetic field (IMF), and proton flux to determine current and forecast geomagnetic conditions.

Kp Index

The planetary Kp index is the standard measure of geomagnetic disturbance on a 0-9 scale. Higher Kp values push the auroral oval further south, making northern lights visible at lower latitudes. We use real-time Kp data and 3-day forecasts from NOAA SWPC to predict aurora visibility across the United States — from Alaska (where Kp 0+ is often sufficient) down to the lower 48 states (which typically require Kp 5+ or higher).

Cloud Cover

Even during strong geomagnetic storms, clouds will block your view of the aurora. We integrate hourly cloud cover forecasts for every US city we track, giving you a realistic picture of whether you will actually see the northern lights tonight. Cloud data updates hourly to capture fast-changing weather.

Moon Phase & Illumination

A bright moon washes out fainter aurora displays. Our algorithm factors in current moon illumination percentage and moonrise/moonset times so you know when skies will be darkest for optimal viewing.

Sky Darkness

Aurora is only visible after dark. We calculate precise sunset, civil twilight, nautical twilight, and astronomical twilight times for each location. During daylight or civil twilight, our forecast automatically shows "Unlikely" regardless of geomagnetic conditions, so you are never misled.

Magnetic Latitude

Geographic latitude alone does not determine aurora visibility — magnetic latitude matters more. Magnetic north is offset from true north, which means some US locations at the same geographic latitude have very different aurora odds. We use up-to-date geomagnetic models to calculate the precise magnetic latitude for every city, then determine the minimum Kp threshold required for aurora to reach that location.

Our Algorithm

Aurora Forecast USA uses a proprietary 5-factor algorithm that combines all of the data sources above into a single, easy-to-understand aurora probability for your location. The five factors are:

Geomagnetic activity — real-time Kp index vs. your location's minimum Kp threshold
Cloud cover — current and forecast sky conditions
Moon illumination — how much moonlight is competing with aurora
Sky darkness — whether it is dark enough to see aurora
Magnetic latitude — your location's position relative to the auroral oval

Each factor is weighted and combined to produce a probability score and status level (from "Unlikely" to "High"). The algorithm is calibrated against historical aurora sightings across the US to ensure accuracy at every latitude.

Update Frequency

Space weather data: every 15 minutes from NOAA SWPC
Cloud cover: hourly updates for all tracked locations
Moon & darkness: calculated in real time based on your location and current date
Kp forecast: 3-hour, 27-day, and monthly outlooks refreshed multiple times daily

Coverage

Aurora Forecast USA covers 38 US states with dedicated forecasts for 300+ cities. Every state has its own page with aurora viewing guidance tailored to local conditions. From prime viewing zones in Alaska to rare-event tracking in the southern states, our state-by-state forecasts help you know exactly what to expect at your location.

Accuracy & Limitations

Aurora forecasting is inherently uncertain because it depends on solar activity that can change rapidly. Our algorithm provides the best estimate given current data, but surprises — both positive and negative — happen regularly. We recommend:

Checking the forecast within 1-2 hours of when you plan to go outside
Monitoring the 3-hour forecast for trend changes
Having a backup plan if cloud cover moves in
Using our app for real-time push notifications when conditions improve

Learn More

Explore aurora forecasts for popular US cities:

Fairbanks, Alaska — prime auroral zone
Anchorage, Alaska — frequent aurora displays
Seattle, Washington — visible during strong storms
Minneapolis, Minnesota — occasional northern lights
Chicago, Illinois — rare but possible during major events
Denver, Colorado — only during extreme storms