Aurora Borealis in Jämsä
Finland · 61.86°, 25.19° · geomagnetic 59.3° · needs Kp 5
Tonight in Jämsä
39%
Peak chance of a visible display tonight, from the same model the Revon app runs. Jämsä needs Kp 5, and tonight the forecast peaks at Kp 5.7. That is on the threshold rather than over it, so cloud and moonlight will decide the night.
Updated 2026-08-02 20:20 UTC
The next 30 nights in Jämsä
Every night to come, scored the same way as tonight. The best of the open week is Sunday 2 Aug at 39%. One of the seven reaches the Kp 5 that Jämsä needs: Sunday 2 Aug, at Kp 5.7. The 23 nights past the seven-day window move with the 27-day solar rotation and are updated daily in the app.
Nights 8–30 unlock in the Revon app
Revon aurora model over the NOAA Kp forecast and 27-day outlook
How often the aurora borealis reaches Jämsä
19.8 nights a year, averaged across 10.0 years of records
| Storm level | Nights / year |
|---|---|
| Kp 4 | 83.4 |
| Kp 5 | 28.7 |
| Kp 6 | 9.3 |
| Kp 7 | 3.2 |
| Kp 8 | 1.2 |
NOAA planetary Kp, 2016-04-02 to 2026-03-30
Worth watching through the dark half of the year
Kp 5 is a moderate storm — not an everyday event, but common enough that a patient observer in Jämsä sees the aurora borealis most winters.
Hours of true darkness, month by month
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 12.2 | 10.2 | 7.4 | 1.5 | 0.0 | 0.0 | 0.0 | 0.0 | 5.8 | 9.3 | 11.7 | 12.7 |
Solar declination and hour angle at −18°
Nothing to see from May to August
Through those months the sun never falls more than 18° below the Jämsä horizon, so the sky never darkens fully. Plan around the darker half of the year.
Getting clear of the light
Jämsä is small enough that its own lights are a minor problem — the centre reads Bortle 5. Walking to the edge of town is often escape enough.
- 13 km south-south-east → Bortle 5
- 15 km north-north-east → Bortle 4
Falchi 2016 World Atlas (DOI: 10.5880/GFZ.1.4.2016.001)
The months that actually deliver
Counting only nights that were both stormy enough and dark enough, September, March and October came out ahead in Jämsä. That is storm season and darkness overlapping — the equinoxes tend to be geomagnetically active, and the nights are already long by then.
Darkest nights of the coming year
A bright moon washes out a weak display as effectively as street lighting. These new moons fall inside the Jämsä viewing season.
- 11 Sep 2026
- 11 Oct 2026
- 09 Nov 2026
- 09 Dec 2026
- 07 Jan 2027
- 06 Feb 2027
- 08 Mar 2027
Where it is close to a certainty
If you would rather plan a trip than wait for a storm, the nearest place with genuinely frequent aurora is Rovaniemi, 516 km north in Finland.
| Jämsä | Rovaniemi | |
|---|---|---|
| Kp needed | 5 | 3 |
| Nights per year | 19.8 | 171.4 |
| Geomagnetic latitude | 59.3° | 63.6° |
Confirmed reports from this area
164 verified sightings were logged within 300 km of Jämsä between 2015-01-01 and 2016-12-31. Rare is not the same as impossible.
Aurorasaurus verified positive reports
Where the horizon opens up near Jämsä
The display sits low on the northern horizon, so what beats a better forecast is open ground facing that way. Height gets you above the town glow; water gives you an unbroken skyline. These are within a short drive of Jämsä.
- Suolammi — lake3.1 km north
- Asemenjärvi — lake3.1 km east
- Pellavassaari — island3.3 km east-north-east
- Suolamminmäki — hill3.3 km north
- Pieni Ahonvuori — hill3.5 km north-north-east
- Hakaniemi — headland3.6 km east-north-east
Places from GeoNames (CC BY 4.0)
The last nights it was visible here
Nights in the last decade when the storm was strong enough for Jämsä and the sky was dark enough to show it.
| Date | Peak |
|---|---|
| 2026-03-24 | Kp 5.0 |
| 2026-03-23 | Kp 5.0 |
| 2026-03-22 | Kp 6.67 |
| 2026-03-21 | Kp 6.0 |
| 2026-03-20 | Kp 7.0 |
NOAA planetary Kp
Know when it is worth going outside
Revon watches the Jämsä forecast and pushes an alert when the odds for tonight clear your threshold — no checking, no guessing.
Common questions about the aurora borealis in Jämsä
Can you see the aurora borealis from Jämsä?
Yes. On the last 10.0 years of NOAA Kp records, Jämsä had about 19.8 nights a year when the storm was strong enough and the sky dark enough at the same time.
What Kp index do you need to see the aurora borealis in Jämsä?
Kp 5. Jämsä sits at geomagnetic latitude 59.3°, and the auroral oval only reaches that far from the pole once activity hits Kp 5. Storms that size occur about 28.7 nights a year.
When is the best time of year to see the aurora borealis in Jämsä?
September, March and October. Those months scored highest once both conditions are counted together: geomagnetic activity and enough hours of real darkness. From May to August the sky over Jämsä never gets fully dark, so nothing is visible however strong the storm.
Where can you escape the light pollution near Jämsä?
The centre of Jämsä reads Bortle 5. The nearest sky at Bortle 4 is about 15 km north-north-east. On a marginal night that drive matters more than the forecast does.
Where is the nearest place to Jämsä with reliable aurora borealis?
Rovaniemi, Finland — 516 km north. It needs only Kp 3 and averages 171.4 viable nights a year against 19.8 in Jämsä.
Nearby towns
Forecasts for places within reach of Jämsä.