The aurora is never guaranteed, but the planetary K index (Kp) is the best short-range guide we have. This page pulls the current Kp, the solar wind and the NOAA three-hourly forecast, so you can judge whether it is worth standing outside at midnight.
Live space weather
Aurora chance from Stornoway
Planetary K index, solar wind and the three-hourly forecast from NOAA SWPC, refreshed every few minutes.
Quiet. Very low. The auroral oval sits too far north for Lewis at this level.
- Next 24 h peak
- 3.3 at 00:00
- Solar wind
- 401 km/s
- Bz
- -2.0 nT
- Bt
- 4.0 nT
- Updated
- 00:20 UTC
Kp forecast for the next three days
Each bar is one three-hour slot in UTC. The height and colour show the forecast Kp, so you can see which nights are worth watching.
Mon 16 NovMax Kp 3.3
Tue 17 NovMax Kp 4.7
Wed 18 NovMax Kp 2.7
Quiet to unsettledActiveStorm, Kp 5 or moreOverhead aurora becomes likely from Lewis at Kp 6 and above; Kp 5 usually means a glow low to the north.
NOAA SWPC Kp data (opens in a new tab)AuroraWatch UK alerts (opens in a new tab)Check the sky on the webcam
Will the aurora be visible in Scotland tonight?
Tonight's forecast peak is Kp 3.3 at 00:00 UTC. Only when the Kp index is high enough and the sky is clear. From Stornoway, Kp 5 usually means a glow low on the northern horizon, while Kp 6 or more can put the aurora overhead. The live panel above shows tonight's forecast peak, and the three-day bars show which nights are worth watching.
- What Kp index do you need to see the northern lights in Scotland?
- Kp 5 is the usual threshold for a chance from northern Scotland, and even then it is often a faint arc low to the north. Kp 6 and above is when overhead displays become likely from the Isle of Lewis. The Kp scale runs from 0 to 9, and each step is a real change in geomagnetic activity.
- What time of night is best for aurora in Scotland?
- The hours around local midnight, roughly 22:00 to 02:00, are darkest and usually best. Aurora can appear at any time after dark when the Kp is elevated, so check the live panel and the webcam rather than waiting for a particular forecast hour.
- Where is the best place to see the aurora on the Isle of Lewis?
- Any dark spot with an open northern horizon. From Stornoway, the coast north of the town and the darker roads towards Ness work well; give your eyes ten minutes to adapt and keep away from street lights. The station webcam looks north from Marybank and shows whether the sky is clear.
Why Lewis is a good place to look
Marybank sits at 58°N, roughly level with southern Greenland. That is far enough north that a modest geomagnetic disturbance puts the aurora on the northern horizon, and a proper storm can bring it overhead. The bigger problem is usually cloud, not latitude.
How to watch from the island
- Get away from lights. The west side of Lewis is darkest: Gallan Head, Uig and the moor above Carloway all have a clear northern horizon.
- Give your eyes 20 minutes. No phone screens, no torches. Faint arcs only appear once your eyes have adapted.
- Look north, low down. From 58°N the aurora often sits just above the horizon as a pale green glow, not overhead curtains.
- Check the cloud first. A clear sky matters more than another point of Kp. The live weather page has the webcam and the short forecast.
- Mind the moon. A bright moon washes out faint arcs; the sun and moon almanac shows moonrise, phase and illumination.
Reading the numbers
Kp runs from 0 to 9 in three-hour steps. At this latitude Kp 3 is worth a look, Kp 4 often gives a visible glow, and Kp 5 or more is a genuine storm with a chance of overhead structure. A strongly negative Bz (southward interplanetary magnetic field) helps: it lets the solar wind couple to the magnetosphere more efficiently, so the same Kp can look better than expected.
Forecasts beyond about an hour are probabilities, not promises. The panel above mixes observed values with NOAA predictions, so treat the later bars as a guide. For alerts to your phone, use AuroraWatch UK.