Live aurora forecast

Northern lights in Bornholm tonight

Baltic Sea, Denmark · 55° magnetic latitude · Kp 5–6 threshold

Aurora visibility · Bornholm
6/9
Possible tonight

Kp 6 is at the threshold for Bornholm. Aurora may be visible from a dark site if cloud cover permits.

QuietStormExtreme
Threshold
Kp 5–6
Magnetic latitude
~55°N
Bz ↓ south
- nT
Solar wind
- km/s
Density
- p/cm³
Cloud
-
Conditions right now: - Kp + Bz + solar wind + cloud + moon

Updated: 6 Jul, 03:20 UTC

7-day outlook for Bornholm

Today
6 Jul
6
Possible
Tomorrow
7 Jul
3
Quiet
Wed
8 Jul
3
Quiet
Thu
9 Jul
3
Quiet
Fri
10 Jul
3
Quiet
Sat
11 Jul
3
Quiet
Sun
12 Jul
3
Quiet

Based on CME arrival predictions from NASA DONKI. Arrival times ±6 hours.

auroratonight.space

What Kp is needed here?

Bornholm sits at a magnetic latitude of approximately 55°N. The Kp index - a global measure of geomagnetic activity on a scale from 0 (quiet) to 9 (extreme storm), updated every 3 hours - needs to reach Kp 5–6 before the auroral oval expands far enough south to be visible from here.

At Kp 5–6, visibility is possible from Bornholm but skies need to be clear and dark. Cloud cover and light pollution remain the main obstacles even when Kp is high enough.

Plan your viewing

Best dark sky sites near Bornholm

Light pollution is the biggest obstacle after cloud cover. These sites give you the best dark northern horizon within reach.

Hammerknuden rocky headland

Get directions ↗
Bortle Class 3 - Rural sky 10 km from Sandvig - approximately 12 minute drive

The northernmost point of Bornholm at the Hammeren peninsula, a granite rocky headland facing north across the Baltic toward Sweden's southernmost point. No settlements lie to the north, and the Hammerhavn harbour 500 m to the south has minimal lighting. Accessible by car to a car park near Hammerfyr lighthouse, then a 10-minute walk on a marked path - the site faces north-northwest with a completely open sea horizon. Once away from the car park lights the headland is genuinely dark, with the granite outcrops providing a distinctive foreground against the northern sky.

Slettebakken viewpoint

Get directions ↗
Bortle Class 3 - Rural sky 5 km from Allinge - approximately 8 minute drive

An elevated coastal heath position on the northwest coast of Bornholm above Allinge, giving open northerly views across Bornholmsgattet toward southern Sweden. The surrounding heath carries no artificial lighting, and Allinge's modest light dome sits to the southeast where it does not affect the northern horizon. A signed viewpoint with a small car park on route 158 makes this accessible year-round on tarmac road. The position reaches Bortle Class 3 from the heath and is the most convenient dark north-facing site close to the island's main tourist settlements.

Almindingen forest clearings

Get directions ↗
Bortle Class 3-4 - Rural sky 20 km from Rønne - approximately 25 minute drive

Denmark's third largest forest, occupying the centre of Bornholm at up to 162 m altitude - the highest point on the island. Forest roads give access to dark clearings away from the perimeter, and the Rytterknægten tower at 162 m provides elevated sky access above the tree canopy. The forest interior reaches Bortle Class 3-4 depending on position within it, with the surrounding heath and farmland outside the forest adding to the overall darkness. Accessible via forest roads from route 34.

When to go

Best time to see the northern lights in Bornholm

At 55°N magnetic latitude, Bornholm sits at the lower end of regular aurora territory. Only the deep mid-winter months of November through January offer nights dark enough for aurora to be visible, and only then when a significant geomagnetic storm pushes the auroral oval this far south.

Activity peaks around the September and March equinoxes, when Earth's magnetic field geometry is most favourable for coupling with the solar wind. Events during these two windows tend to produce the strongest displays of the year for observers at Bornholm's latitude.

Outside November through January, twilight is too bright for aurora viewing even during significant storms. The season is short, but the equinox months on either side of winter can extend it slightly when storm timing aligns.

Up to 8 locations

Bornholm

Denmark

Possible
Kp 6 need Kp 5
Checking darkness…
Copenhagen

Denmark

Possible
Kp 6 need Kp 5-6
Checking darkness…
Skagen

Denmark

Good chance
Kp 6 need Kp 3-4
Checking darkness…
The odds

How often does the aurora appear in Bornholm?

Average nights per month the Kp reached Bornholm's threshold of 5+, from 15 years of geomagnetic data (2010–2024).

1.2Jan
1.3Feb
1.6Mar
1.4Apr
0.3May
0Jun
0Jul
1.2Aug
1.5Sep
1.5Oct
1.2Nov
1.1Dec

Counts the Kp 5+ threshold only - cloud cover and local darkness are not included.
Kp data: GFZ German Research Centre for Geosciences, CC BY 4.0

Make it happen

Plan your trip to Bornholm

Based on 15 years of geomagnetic data (2010–2024)

1st
March
1.6
avg aurora nights
Requires an extended stay
2nd
September
1.5
avg aurora nights
Requires an extended stay
3rd
October
1.5
avg aurora nights
Requires an extended stay

Best window

The February to April window averages 4 aurora nights - the strongest consecutive stretch of the year.

How long to stay

Aurora at this latitude requires patience - allow as many nights as possible during March.

Questions

Common questions about aurora in Bornholm

What Kp is needed for northern lights from Bornholm?
The Kp index is a global measure of geomagnetic activity on a scale from 0 (quiet) to 9 (extreme storm), updated every 3 hours. Bornholm at 55°N magnetic latitude - the same band as Flensburg in Germany and Newcastle in England - needs Kp 5 from dark coastal sites. The north coast at Hammerknuden gives the best threshold of any position on the island. During G1 storms (Kp 5), the auroral oval extends to around 55°N magnetic latitude and a green arc becomes detectable on the northern horizon from dark sites. Strong G2 events (Kp 6) bring structural aurora with rays and bands.
How does Bornholm compare to Copenhagen for aurora?
Bornholm sits approximately 1.5 degrees further north than Copenhagen at 55°N versus 56°N magnetic latitude, which reduces the effective Kp threshold by around half a point. The more significant advantage is dark sky. Bornholm has around 40,000 permanent residents and no major light pollution sources on its north coast. Copenhagen's metropolitan area creates a sky glow that raises the practical threshold to Kp 6-7. From the north coast of Bornholm, Kp 5 conditions produce aurora detectable with the naked eye.
How do I get to Bornholm?
Bornholm is served by Bornholmstrafikken ferries from Rønne harbour - the main route runs from Ystad in Sweden (80 minutes) and Copenhagen's Nordhavn (5 hours). Stena Line also operates routes from Sassnitz in Germany. Direct flights operate from Copenhagen airport year-round with BornholmFly, taking 45 minutes. The island has a limited bus network; a hire car is necessary for reaching the north coast dark sky sites independently. Sandvig and Allinge, the two settlements closest to Hammerknuden, are 10 km from Rønne.
Is Bornholm's north coast good for aurora photography?
The granite rock formations at Hammerknuden give a distinctive foreground for aurora images - the angular Baltic granite outcrops are different from the sandy or cliff coastlines of the Danish mainland. The north-facing aspect gives a clear horizon over the Bornholmsgattet with southern Sweden 40 km away, too far to contribute any light pollution. The Hammerfyr lighthouse tower provides a vertical element in compositions. Long autumn nights give 8-10 hours of darkness and the island's clear maritime air gives better transparency than inland positions at the same latitude.
When is aurora season on Bornholm?
September to March. The equinox months of September-October and February-March give the highest probability of combining elevated geomagnetic activity with adequate darkness. Bornholm's Baltic position gives it more stable, colder winter air than Denmark's west-facing Jutland coast, which catches more Atlantic cloud. February and March particularly benefit from cold, clear high-pressure systems that sit over the Baltic for days at a time.
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