Northern lights: how to tell if you’ll see them, and where

Northern lights from the UK: rarer the further south you are

In May 2024, the northern lights reached southern parts of the UK, as the Met Office later recalled [27]. Across the Channel, Météo-France logged them in its monthly climate bulletin for Brittany, with a photo taken at Cesson-Sévigné, near Rennes: barely visible to the naked eye, but spectacular on photos exposed for 8 to 10 seconds [1]. On the night of 10 to 11 May, according to a research dataset published in 2025, they were seen as far south as the Côte d’Azur [2].

That night, Earth was weathering its strongest geomagnetic stormA major disturbance of Earth’s magnetic field, triggered by a surge of energy from the solar wind, the stream of particles the Sun gives off all the time. in two decades [3], and the index that measures these storms hit the top of its scale [4]. That extreme level, which the US agency NOAA calls G5, is rare: over a solar cycle of about 11 years, it counts 4 days of G5 storms on average, and 60 days of G4, the level just below [5]. In the far north of Scotland, the British Geological Survey reckons you might see aurora every few months on average, and less often further south [24]. So the real question isn’t whether the aurora can be seen from the UK, but how to know, in time, whether the next one will reach you.

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The Kp index and the G scale: what the numbers mean

Every aurora forecast revolves around one index: Kp. It measures how disturbed Earth’s magnetic field is over 3-hour periods, on a scale from 0 to 9: 1 means calm, 5 or more a geomagnetic storm [6]. The ‘K’ comes from the German Kennziffer, ‘characteristic digit’, and the ‘p’ stands for planetary: it is the average of 13 observatories between 44° and 60° geomagnetic latitudeLatitude measured from the geomagnetic pole, which is tied to Earth’s magnetic field, rather than from the geographic North Pole., in both hemispheres [6].

The official index is calculated by GFZ, the German geosciences research centre in Potsdam, to which NOAA itself refers [6]. It comes in thirds of a unit, 28 values in all, from 0o to 9o by way of 8+ and 9-, as described by the international service that distributes these indices, hosted in Strasbourg [7]. Since each step is a third, 9- can also be written 8.67. NOAA publishes its own estimate alongside, updated every minute from just 8 magnetometers, one of them at Hartland in the UK [6].

For the public, NOAA translates these values into five storm levels: G1, minor, at Kp 5; G2, moderate, at Kp 6; G3, strong, at Kp 7; G4, severe, at Kp 8 and 9-; G5, extreme, at Kp 9o [6, 5].

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Why a US threshold doesn’t carry over to the UK

The catch comes down to one word: geomagnetic. NOAA’s scale places the aurora seen during a G3 storm as far south as Illinois and Oregon, typically around 50° geomagnetic latitude, and during a G5 storm as far as Florida and southern Texas, around 40° [5]. NOAA spells it out for its rule of thumb: the link between Kp and the aurora holds in geomagnetic latitude, not geographic [8].

And the geomagnetic pole isn’t the North Pole. The British Geological Survey’s public calculator, based on the International Geomagnetic Reference Field, makes the comparison possible: at the same geographic latitude, places in the UK and Ireland come out further south than places in North America [9]. With the tool’s main calculation, London, at 51.5° N, sits at about 47° geomagnetic latitude, and Edinburgh, at 56° N, at about 53°; New York, at 40.7° N, comes out at about 49°.

So a threshold written for the US doesn’t carry over to the UK as it stands. NOAA also gives an average rule: the southern edge of the auroral ovalThe ring centred on each geomagnetic pole where aurora forms; it widens towards the equator during storms. moves about 2° of geomagnetic latitude per Kp point, from 66° at Kp 0 to 48° at Kp 9, an approximate relationship that represents an average, it stresses [8]. But a bright aurora can be seen from a long way off, up to about 1,000 km [10]. From the UK, that is often how it appears: during moderate to strong storms, the aurora moves across southern Iceland or towards the Faroes, and can be faintly visible from here because it sits so high, the Met Office explains [14]. Further south, even during the storm of 12 November 2025, the auroral oval did not reach central Europe, the Austrian news agency APA reported, drawing on specialists at GeoSphere Austria [11].

The thresholds published for the UK

For the UK, the Met Office publishes rough Kp thresholds. Across the Channel, France has no official one: neither Météo-France nor any other public body publishes a minimum Kp for seeing an aurora. Belgium and Switzerland give figures of their own, and the lowest of them describe a faint glow low on the horizon.

The detail that changes everything: these minimum thresholds describe a glow, often red, low on the horizon. The displays that made the news came with far stronger storms. On 19 January 2026, when a G4 storm brought vivid aurora widely across the UK wherever skies were clear [26], the official Kp reached 9- [4]; the Royal Observatory of Belgium photographed it from Brussels between 9.30pm and 10.15pm UT [12]. In May 2024, when the aurora reached southern parts of the UK and was seen as far as Belgium [27, 15], Kp hit 9o, the very top of the scale [4].

Official forecasts: 3 days, 27 days, 30 minutes

In the UK, the Met Office runs a Space Weather Operations Centre around the clock, every day of the year [26], and its space weather page carries aurora forecasts and a four-day summary [28]. Upstream, NOAA’s Space Weather Prediction Center, the US government’s official source for space weather forecasts [3], publishes three products worth knowing:

• The 3-day forecast, issued every 12 hours, at 12.30am and 12.30pm UT: the expected Kp for each 3-hour period, in Universal Time, with a short explanation from the forecaster [16]. UT is the same as GMT: during British Summer Time, add an hour.
• The 27-day outlook, issued on Mondays: a single Kp per day, the highest expected [17]. It helps you spot an unsettled spell, not pick an evening.
• The OVATION map: the likely location and intensity of the aurora over the next 30 to 90 minutes, the time the solar wind, measured by satellites stationed between the Sun and Earth, takes to reach us [10].

What doesn’t exist: an official aurora forecast 7 days ahead, let alone one for your postcode. NASA sums up the limit: scientists can sometimes tell a day or two in advance that aurora is possible, but only when the cloud of particles reaches the monitoring satellites, about an hour before Earth, do they know the orientation of its magnetic field, which is critical for knowing where aurora may be seen [18]. AuroraWatch UK, for its part, only issues real-time alerts and refers its users to NOAA for predictions [29].

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NOAA also publishes an experimental aurora forecast for tonight and tomorrow night, but only over North America. Its ‘viewline’, a visibility line drawn on the map, was removed in May 2026 [20]: any article that sends you there predates the change.

Getting alerted: AuroraWatch UK, NOAA and the apps

In the UK, the alert to sign up for is AuroraWatch UK’s. Run by Lancaster University, it triggers its alerts from the measurements of two magnetometer networks, SAMNET and AuroraWatchNet, on a four-colour scale. At amber, aurora is likely to be visible by eye from Scotland, northern England and Northern Ireland, and photographs are likely from anywhere in the UK; at red, aurora is likely to be visible by eye and camera from anywhere in the UK [22].

For the forecast side, NOAA emails its alerts, watches and warnings to subscribers within moments of issuing them [21]. For the magnetic field, a watch goes out when the highest Kp predicted for a day reaches 5, 6, 7 or 8 and above; a warning when a Kp of 4 to 7 or more is expected; an alert when the estimate reaches 4, 5, 6, 7, 8 or 9 [6].

As for apps, check where their data comes from. AuroraWatch UK’s apps, written by third-party developers, use the same data as the service’s own alerts [22]. In 2016, NASA described Aurorasaurus, a citizen science project that plotted observers’ reports against a visibility line calculated with the OVATION model. After analysing 500 reports from spring 2015, its team found that many people saw the aurora further south than the model suggested [23].

Where and when to look: dark skies, a clear view north, around midnight

The aurora sits hundreds of kilometres up, well above the clouds, so you need a clear sky [24]. Then darkness: away from street lights, and ideally without a full moon, which dims the aurora’s apparent brightness [8]. Look for an unobstructed view to the north, from a hilltop or the coast, for instance [24]: from high ground, you can spot an aurora that sits 1,000 km further north [8]. During extreme storms, look overhead too, and even to the south [24]. The same conditions, a clear sky, real darkness and little moonlight, also make for good meteor shower nights.

As for timing, the best window is usually within an hour or two of midnight, between 10pm and 2am local time [8]. During big events, aurora can appear as early as sunset and as late as sunrise [18]. Storms also tend to be stronger around the spring and autumn equinoxes [8]. An aurora night is mostly a long wait, head tilted back, with the cold creeping up from your ankles.

If you’re tempted to wait for the aurora all night, check first that you’re allowed to stay where you are, and pack a sleeping bag suited to the cold forecast. In Sweden, Norway and Finland, the rules come from the right of public access.

By eye or by phone: why the camera sees more than you do

Good news: faced with a faint aurora, your phone sees better than you do. At night, the eye relies on its rods, cells that are very sensitive but can’t tell colours apart, and it takes about half an hour to adjust fully to the dark [25]. A faint aurora then looks white or grey, while a long-exposure photo brings out its greens, reds or purples [24].

That is why aurora photos often look far brighter than the sky does to the naked eye: the camera, on a tripod, gathers light for several seconds, just as when photographing the Milky Way, the Met Office explains [14]. Météo-France described exactly that in Brittany in May 2024 [1].

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The solar cycle: what 2026 and 2027 hold

The Sun follows a cycle of about 11 years. The current one, cycle 25, peaked in October 2024, going by the sunspot number tracked by the Royal Observatory of Belgium [15]. That doesn’t spell the end of the aurora: strong storms also happen, less often, during the declining phase, NASA pointed out when it announced, with NOAA, that the Sun had reached its maximum period [3]. In January 2026, the Met Office still expected G4 storms a couple of times a year at this stage of the cycle [26].

On 19 January 2026, a G4 storm did just that, bringing vivid aurora widely across the UK wherever skies were clear, with reports as far south as northern Italy [26]. In December 2025, Christian Möstl, head of GeoSphere Austria’s space weather office, estimated that 2026 could bring three to five storms strong enough for aurora in central Europe [11]. Since the January storm, it has been quiet: from 22 January to 30 September 2026, the official Kp did not exceed 7o, the G3 level [4].

So keep the Met Office space weather page and NOAA’s 3-day forecast to hand, and sign up for AuroraWatch UK alerts. The evening an amber alert or a G4 watch comes through, check the cloud forecast, find a dark spot facing north, a blanket round your shoulders and your phone on a tripod: the next aurora might just turn your horizon pink.

Nolwenn Bastide

Trail running, snow, water, nature and destinations

Nolwenn covers trail running, snow, water, nature and destinations for Outfarer. Curious about everything, from meteor showers to night-train timetables, she has a knack for unearthing the one detail that changes everything, and putting it in a single sentence.

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