Frequently Asked Questions

The aurora is created when charged particles from the Sun, carried by the solar wind, are funneled by Earth’s magnetic field toward the polar regions. There they collide with oxygen and nitrogen in the upper atmosphere, and those gases release energy as light. The result is the shifting glow we call the aurora.

They are the same phenomenon in different hemispheres. Aurora borealis is the northern lights, seen around the Arctic. Aurora australis is the southern lights, seen around Antarctica and the far south of New Zealand, Australia, and South America.

Color depends on which gas is glowing and at what altitude. Green, the most common color, comes from oxygen at around 100 to 300 kilometers up. Red comes from oxygen at higher altitudes, while blue and purple hues come from nitrogen. During strong displays you may see several colors at once.

Most auroral light is produced between roughly 100 and 300 kilometers above the ground, far higher than clouds or weather. This is why a clear sky matters so much: clouds sit well below the aurora and simply block the view.

Reports of faint crackling or whooshing sounds during very strong displays have existed for a long time, and some research suggests low-altitude electrical discharges could explain them. However, audible aurora is rare and not something most viewers will ever experience.

Not guaranteed, but in cities directly under the auroral oval such as Tromso or Fairbanks, some auroral activity occurs on a large share of dark, clear nights during the season. The main obstacles are cloud cover and daylight rather than a lack of activity.

The hours around local midnight, roughly 9 PM to 2 AM, tend to be the most active. That said, displays can happen any time the sky is dark, so it is worth checking conditions throughout the night.

In the northern hemisphere the season runs roughly from late August to early April, when nights are long and dark. The southern hemisphere is the opposite. Aurora activity itself happens year-round, but you cannot see it when the sky never gets dark.

A bright full moon can wash out fainter auroras, much like light pollution. Strong displays remain easy to see, but for the best chance with weaker activity, darker nights around the new moon are ideal.

A high Kp value only means geomagnetic activity is strong. You also need a dark sky and clear weather. Daylight, thick cloud, or heavy light pollution will all prevent you from seeing the aurora regardless of the Kp number.

Yes, for the best experience. Light pollution drowns out fainter auroras. A short drive away from town to a dark location with an open view toward the pole greatly improves what you can see, especially on quieter nights.

It varies widely. A display might be a brief glow lasting a few minutes, or an active show with waves and curtains that continues on and off for several hours. Patience is rewarded, since the aurora often brightens in sudden bursts called substorms.

The Kp index refreshes every minute, and the OVATION aurora model updates roughly every few minutes. Pages on this site revalidate about once a minute, so you are always seeing near real-time conditions.

All space weather data comes from the NOAA Space Weather Prediction Center (SWPC), a public source. This includes the Kp index, the OVATION auroral model, and official storm alerts. We process this data into city-level forecasts.

It is a 0 to 100 estimate of how favorable conditions are right now for a given city. The score combines the auroral activity overhead, whether the current Kp meets that city’s visibility threshold, and whether the sky is currently dark.

The most common reason is daylight. If it is currently bright at that location, the score is capped low no matter how strong the activity, because the aurora cannot be seen against a bright sky. The score will rise again after dark.

Yes. The forecast, maps, and city pages are completely free. The site is supported by advertising and by affiliate links for travel bookings, which carry no extra cost to you.

We currently provide dedicated forecast pages for eleven aurora destinations across Norway, Sweden, Finland, Iceland, Canada, the United States, and New Zealand. The live map covers the entire globe.

The Kp index is a global scale from 0 to 9 that measures geomagnetic activity. Higher values mean the auroral oval expands toward the equator, making the aurora visible from lower latitudes. It is calculated every three hours from magnetometers worldwide.

It depends on your geomagnetic latitude. Far-northern places may see aurora at Kp 1 to 2, mid-northern locations might need Kp 4 to 5, and lower latitudes may require a strong storm of Kp 7 or higher. Each city page on this site lists its own threshold.

When geomagnetic activity becomes strong enough, NOAA classifies it as a storm on a G1 to G5 scale, corresponding roughly to Kp 5 through 9. Higher G-levels push the aurora further toward the equator and can affect power grids and satellites.

OVATION is a NOAA model that estimates the probability of auroral activity across a global grid for the next 30 to 90 minutes. Aurora Calculator uses it to show the live aurora map and to estimate conditions over each city.

Short-term forecasts of about 30 to 60 minutes, based on solar wind measurements, are reasonably reliable. Longer-range outlooks are more uncertain because the Sun’s behavior is hard to predict. Treat any forecast as a guide, not a guarantee.

Detailed forecasts are practical up to about three days ahead. NOAA also publishes a longer 27-day outlook based on the Sun’s rotation, but it is approximate. Activity simply cannot be predicted reliably months in advance.

Plan at least three nights, and more if you can. Weather is the biggest variable, and a longer stay gives you more chances to catch a clear, active night. Many travelers who stay only one or two nights miss out simply due to cloud cover.

Places directly under the auroral oval with dry, clear climates tend to perform best, such as Fairbanks, Yellowknife, and Abisko. Our trip planner ranks destinations for any given month based on season, latitude, and other factors.

Generally no, at least not in the classic northern destinations. During the high-latitude summer the sky never gets fully dark, so even strong activity is invisible. Aim for the darker months of autumn through early spring.

Both work. A guided tour helps with transport to dark locations and reading the conditions, which is useful for first-time visitors. Independent travelers with a rental car and a good forecast can do very well on their own.

Dress in warm layers, since you may stand still outdoors for long periods in the cold. Bring a tripod if you want photographs, as aurora shots need long exposures. A hot drink and patience also go a long way.

For many people it is a memorable experience, but success is never guaranteed on any single trip. The best approach is to choose a destination and season that stack the odds in your favor, stay several nights, and enjoy the wider winter landscape as part of the trip.