Aurora Borealis in Lahti

Finland · 60.98°, 25.66° · geomagnetic 58.4° · needs Kp 5

Tonight in Lahti

39%

Peak chance of a visible display tonight, from the same model the Revon app runs. Lahti 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.

Tonight Sun 02 Aug
39%
18
20
22
00
02
04
06
Tomorrow Mon 3 Aug
4%
Hour-by-hour for this night is in the app
Tuesday Tue 4 Aug
2%
Hour-by-hour for this night is in the app

Unlock every hour in the app

Updated 2026-08-02 20:20 UTC

The next 30 nights in Lahti

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 Lahti 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.

Moderate aurora activity tonight around midnight. Similar conditions expected on August 19th.

Sun 2
39%
Kp 5.7
Mon 3
4%
Kp 3.3
Tue 4
2%
Kp 2.0
Wed 5
15%
Kp 3.0
Thu 6
3%
Kp 3.0
Fri 7
3%
Kp 2.0
Sat 8
2%
Kp 2.0

Nights 8–30 unlock in the Revon app

See all 30 nights for Lahti

Revon aurora model over the NOAA Kp forecast and 27-day outlook

How often the aurora borealis reaches Lahti

20.1 nights a year, averaged across 10.0 years of records

Storm levelNights / year
Kp 483.4
Kp 528.7
Kp 69.3
Kp 73.2
Kp 81.2

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 Lahti sees the aurora borealis most winters.

Hours of true darkness, month by month

JanFebMarAprMayJunJulAugSepOctNovDec
12.110.27.52.40.00.00.00.06.19.411.612.6

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 Lahti horizon, so the sky never darkens fully. Plan around the darker half of the year.

Getting clear of the light

The sky over Lahti reads Bortle 6. Getting clear of the built-up area makes a visible difference on a marginal night.

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 Lahti. 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 Lahti viewing season.

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, 614 km north in Finland.

LahtiRovaniemi
Kp needed53
Nights per year20.1 171.4
Geomagnetic latitude58.4° 63.6°

See the Rovaniemi forecast

Confirmed reports from this area

41 verified sightings were logged within 300 km of Lahti 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 Lahti

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 Lahti.

Places from GeoNames (CC BY 4.0)

What to do with the daylight

Aurora watching is a night job, and in winter that leaves a short, bright day to fill. Close to Lahti you will find Hollola TV Mast, Hiidenlähde and Lahti transmitter, Tower 2, and for a day when the cloud sits low, Lahden Historiallinen Museo, Hiihtomuseo and Suomen Moottoripyörämuseo are indoors and near by.

Keep the daylight loose: the sky decides the evening, and the forecast can turn within a few hours.

Places from GeoNames (CC BY 4.0)

Where to stay

Anywhere on the outskirts of Lahti will do; what matters is being able to step outside and check the sky without a drive first.

Places from GeoNames (CC BY 4.0) — confirm before booking

The last nights it was visible here

Nights in the last decade when the storm was strong enough for Lahti and the sky was dark enough to show it.

DatePeak
2026-03-24Kp 5.0
2026-03-23Kp 5.0
2026-03-22Kp 6.67
2026-03-21Kp 6.0
2026-03-20Kp 7.0

NOAA planetary Kp

Know when it is worth going outside

Revon watches the Lahti forecast and pushes an alert when the odds for tonight clear your threshold — no checking, no guessing.

Get aurora alerts on iPhone

Common questions about the aurora borealis in Lahti

Can you see the aurora borealis from Lahti?

Yes. On the last 10.0 years of NOAA Kp records, Lahti had about 20.1 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 Lahti?

Kp 5. Lahti sits at geomagnetic latitude 58.4°, 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 Lahti?

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 Lahti never gets fully dark, so nothing is visible however strong the storm.

Where can you escape the light pollution near Lahti?

The centre of Lahti reads Bortle 6. The nearest sky at Bortle 4 is about 30 km north around Asikkala. On a marginal night that drive matters more than the forecast does.

Where is the nearest place to Lahti with reliable aurora borealis?

Rovaniemi, Finland — 614 km north. It needs only Kp 3 and averages 171.4 viable nights a year against 20.1 in Lahti.

Nearby towns

Forecasts for places within reach of Lahti.