PLAN YOUR NIGHT
Check tonight’s conditions, then plan ahead with the seven-night calendar.
Dark, 10% cloud and activity present overhead.
Darkness, limited cloud cover and modelled northern lights activity line up. Find an open view and give your eyes time to adjust.
THE REST OF THIS NIGHT
How we rate the chance
Dark, under 35% cloud and active: Kp 3 or more in the NOAA outlook, or activity present overhead right now.
One thing is borderline: patchy cloud (35–75%), twilight, quiet activity (Kp 0–2) or no activity forecast yet.
75% cloud or more. The sky is mostly covered, whatever the activity.
The sun is less than 6° below the horizon.
Each column is an actual forecast time; later forecasts may be six hours apart. Darkness means the sun is at least 12° below the horizon, and twilight 6–12° below. Northern lights can appear at high latitudes even when Kp is low.
PLAN THE NIGHTS AHEAD
Each night shows its viewing chance and the best time to look. Choose a night to see it hour by hour. All times are local to Tromsø.
Cloud ranges use available forecast samples during dark hours. Later nights have fewer samples and greater uncertainty. The viewing chance is a rating of conditions, not a guarantee of a sighting.
NOAA three-day outlook · issued 28 Oct, 12:30 UTC
MET Norway · issued 28 Oct, 18:30 UTC
Estimated index for a three-hour period
Quiet. Typical for most nights. Northern lights can still appear at high latitudes when Kp is low.
Speed measured upstream of Earth
Slow. Typical background speed.
Southward field · supports activity
South. Supports activity, best when it lasts.
KNOW WHAT TO LOOK FOR
A fully dark sky
Faint northern lights only show after twilight, when the sun is at least 12° below the horizon. In Tromsø tonight that is from 18:00 to 05:30.
Helps now: Now: dark
Under 35% cloud
Cloud is the most common reason to miss a display. Between 35 and 75%, look for breaks.
Helps now: Now: 10% cloud
Kp 3 or more
Helps, but it is a global index. Northern lights can appear at high latitudes even when Kp is low.
Helps now: Now: present overhead
Bz south, fast wind
A southward Bz that lasts, especially with solar wind over 500 km/s, adds energy.
Borderline now: Now: Bz -4.5 nT, 403 km/s
An Arctic island city surrounded by fjords and mountains. Compare cloud forecasts before choosing a direction for the evening.
