Bretagne

Northern lights in Rennes tonight

Real-time aurora forecast for Rennes (Bretagne) - latitude 48.12° N, estimated Kp threshold 7.

Kp index

4.3

unsettled

Hemispheric power

North21GW

South22GW

Source: app.pulsar-si.com

Tonight in Rennes

Very unlikely

Based on Kp 4.3 and Rennes's latitude.

Seeing the northern lights from Rennes

Rennes, at 48.1° N, benefits from Brittany's relatively northern position. The observation threshold is around Kp 7. The Breton countryside quickly offers dark skies outside the city, and the north coast (Saint-Malo, Cancale, Cap Fréhel) allows seaside observation with a northern horizon over the Channel. The May 2024 storm produced a particularly colourful aurora from Ille-et-Vilaine's high points.

Observation conditions in Rennes

Rennes is rated Bortle 6, friendlier than Nantes or Brest thanks to its moderate size. The Paimpont forest (Bortle 4, 40 km), the Monts d'Arrée further on (Bortle 3, 150 km) and the Trégor coast (Bortle 3, 110 km north-west) offer remarkable skies. The Breton oceanic climate is capricious: cloud cover changes fast, a clear sky can open within hours.

Recent auroras from Rennes

10-11 May 2024 (Kp 9): colourful aurora photographed from the Emerald Coast and the Cotentin. 5 November 2023 (Kp 7): sightings from the Brétillienne countryside. 8 September 2017 (Kp 7.7).

What Rennes asks of the sky

Geomagnetic latitude

50.3°

13 of 40

Kp index required

Kp 7

9 / 12 months

Dark nights per year

365

365 / 365

Rennes ranks 13 of the 40 cities we track, at 50.3° geomagnetic. Paris sits 0.1° higher , Lorient follows at 50.2°.

The threshold to clear here is Kp 7. Twelve months of archive hold 9 nights, the most recent on 4 July 2026, and 157 since 1994. Brest and Quimper and Saint-Malo share exactly the same threshold.

Rennes keeps full astronomical night all 365 nights of the year, which every city north of the Loire loses for part of the summer.

How to read the Kp index →

Local conditions

Light pollution

Bortle 7 of 9

SQM 18.59 mag/arcsec²

Nearest darker sky

Villeneuve

2 km · Bortle 6

Kp forecast, next 3 days

Source: app.pulsar-si.com. For an aurora to be visible from Rennes, Kp must exceed 7.

Wed 19 Aug

1.1

Expected max Kp

Thu 20 Aug

1.5

Expected max Kp

Fri 21 Aug

1.7

Expected max Kp

Frequently asked questions

Can you see the northern lights from Rennes?

Yes, but rarely. Typically a Kp index of ≥ 7 is needed for the aurora to become visible from Rennes (latitude 48.1° N). Major geomagnetic storms (Kp 8-9) that reach this latitude happen only a handful of times per 11-year solar cycle.

What Kp index is needed to see auroras from Rennes?

The approximate Kp threshold for Rennes is 7. Below that, auroras stay confined to high latitudes (Norway, Scotland). Above it, they gradually extend southward. A Kp of 8 gives a fair chance, 9 a strong one.

When is the best time to watch from Rennes?

Auroras are a nighttime phenomenon, best observed between roughly 10 PM and 2 AM local time, when the geomagnetic pole is tilted towards the Earth's night side. In practice, peaks depend on when a coronal mass ejection arrives - activity can spike at any hour.

Where around Rennes offers better conditions?

Move at least 40-60 km north of Rennes to escape urban light pollution and gain 1-2 magnitudes of limiting magnitude.

Nearby cities

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