Northern lights on Senja tonight
Senja tonight, clouded out.
- Kp you need
- 1+
- Peak tonight
- 4.7
- Cloud, clearest
- 100%
- Dark · UTC+2
- 20:13–05:00
The Kp is enough; the cloud isn't. Clearest: Bergsbotn, cloud at 100%. Moon 62% · aurora probability now 0%.
The Senja watch point →Tonight · clearest first
6 places- 1Bergsbotn100%cloudcloud 100% · the platform over the fjord
- 2Finnsnes100%cloudcloud 100% · the bridge town · where trips start
- 3Gryllefjord100%cloudcloud 100% · west coast · steep peaks
- 4Mefjordvær100%cloudcloud 100% · northern tip · open sea
- 5Straumsnes100%cloudcloud 100% · a quiet jetty · water all round
- 6Tungeneset100%cloudcloud 100% · north coast · the boardwalk
Bars: clear sky over each place's dark window tonight (Open-Meteo). Coast: Natural Earth 1:10m (public domain).
- BergsbotncloudOn Senja's national scenic route, a 44-metre timber platform jutting over the fjord. Dark and usually empty.cloud 100% · 20:14–04:59Tonight →
- FinnsnescloudThe town at the bridge, where most trips onto the island start — the Hurtigruten and the express boat from Tromsø stop here.cloud 100% · 20:11–04:58Tonight →
- GryllefjordcloudThe west coast under steep peaks; the summer ferry to Andøya leaves from here.cloud 100% · 20:15–05:01Tonight →
- MefjordværcloudThe fishing village on the island's northern tip, past Senjahopen — open sea to the north.cloud 100% · 20:14–04:59Tonight →
- The book's frames
Cloud over every place tonight.
This week · Senja
Kp and cloud reach three nights out · UTC+2| Tonight | Tue 20 | Wed 21 | Thu 22 | Fri 23 | Sat 24 | Sun 25 | |
|---|---|---|---|---|---|---|---|
| Call | cloud | maybe | — | — | — | — | — |
| Dark | 8.8 h | 8.9 h | 9.0 h | 9.2 h | 9.3 h | 9.4 h | 9.6 h |
| Moon | 62% | 72% | 81% | 89% | 95% | 98% | 100% |
| Kp / cloud | 4.7 · 100% | 3.7 · 0% | — | — | — | — | — |
Darkness and the moon are astronomy — exact for all seven nights. Kp is NOAA's forecast peak over each dark window, cloud Open-Meteo's mean; both reach about three nights out (2 of 7 here). Whole-season calendar →
Reading the field under the auroral oval…
How it works
A magnetometer measures the Earth’s magnetic field. When a substorm surges the electric current that runs about 100 km up along the auroral oval, the field on the ground beneath it drops by hundreds of nanotesla (nT) within minutes — the sharp dip a magnetogram shows.
This reads the nearest of the Finnish Meteorological Institute’s eight magnetometers, Kilpisjärvi, against its own last 24 hours: 150 nT either way is active, a 300 nT drop a substorm, 600 a strong one. It measures the sky over the station — up to about 300 km away it still speaks for yours — and says nothing about cloud. Kp and Hp30 are planetary; this is local, and minutes old.
Clear sky by month · Senja
Clearest dark months: Jan, Mar, Sep.
ERA5 2015–24, 100 − mean cloud cover — climatology, not a forecast · faint: no dark nights · Best month, all spots →
Senja in numbers
- for a glow
- Kp 1
- overhead
- Kp 3
- geomagnetic
- 66.5°
- Kp 1+ days, last year
- 361 / 365
From the book
Each place, its own page
Questions people ask
Can you see the northern lights on Senja?
Yes. Senja sits at about 66.5° geomagnetic latitude, under the auroral oval: from a dark spot about Kp 1 brings a glow on the northern horizon and roughly Kp 3 puts aurora overhead. On most nights the limit is the cloud, not the Kp.
Senja or Tromsø?
The Kp you need is the same — the two lie under the same oval, 70 km apart as the crow flies. What Senja has is darkness: no city glow, empty platforms and jetties facing the open sea to the north. The weather is the same coastal weather; on ten years of ERA5 Senja's months are about as cloudy as Tromsø's, a few points less each month. When the whole island is clouded, the door above names the clearest place within reach — Tromsø, Skibotn, Abisko or Kilpisjärvi.
When is the aurora season on Senja?
It is dark enough for a bright display from about 1 September to 10 April, and fully dark from mid-September to late March. Polar night, about 30 November to 12 January, means no sunrise, not twenty-four hours of dark. The ten-year cloud record is on the strip above, month by month — and you also need a low moon: the season sheet lists the dark, moonless weeks.
Driving on Senja in winter?
The island's north side is a National Scenic Route — Bergsbotn's platform is on it — which means narrow roads, tunnels and black ice in winter. Check the roads before you set out (Statens vegvesen, vegvesen.no/trafikk). Never stop on the road for the lights: use the parking areas, and wear a reflector.
About this page
A live call for each of six places on Senja — the Kp, tonight's dark window, the cloud over each — ranked clearest first: Tungeneset and Mefjordvær on the north coast, Gryllefjord in the west, Finnsnes at the bridge, and the book's two frames, the Bergsbotn platform and the Straumsnes jetty, each with its own page and photograph. When the whole island is clouded, the door opens on the clearest place within reach.
All six need the same Kp — about 1 for a glow, 3 overhead — so what tells them apart is the cloud: the mountains split the island's weather, and the outer coast and the bridge side can be under different skies on the same night.
Each call is the site's own: NOAA's Kp against each place's threshold (from its geomagnetic latitude), Open-Meteo's cloud over its dark window tonight, the darkness and the moon. Times are local. History: the GFZ definitive Kp record, the last 365 days. Coast: Natural Earth 1:10m (public domain).