Aurora Borealis in Caerphilly
United Kingdom · 51.57°, -3.22° · geomagnetic 53.9° · needs Kp 7
Tonight in Caerphilly
6%
Peak chance of a visible display tonight, from the same model the Revon app runs. Caerphilly needs Kp 7 to see anything at all, and tonight the forecast peaks at Kp 5.7. Short of the threshold, which is what most nights look like here.
Updated 2026-08-02 20:20 UTC
The next 30 nights in Caerphilly
Every night to come, scored the same way as tonight. The best of the open week is Sunday 2 Aug at 6%. Not one of the seven reaches the Kp 7 that Caerphilly needs, which is normal rather than unlucky — it averages 2.7 viable nights a year. 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
See all 30 nights for Caerphilly
Revon aurora model over the NOAA Kp forecast and 27-day outlook
How often the aurora borealis reaches Caerphilly
2.7 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
Wait for an alert; do not book a week
At Kp 7, Caerphilly needs a severe geomagnetic storm before anything shows above the northern horizon. Storms that size arrive a handful of times per solar cycle and announce themselves a day or two ahead. Watching for one beats picking dates and hoping.
Hours of true darkness, month by month
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 11.7 | 10.3 | 8.5 | 5.9 | 2.2 | 0.0 | 0.0 | 4.7 | 7.6 | 9.8 | 11.3 | 12.0 |
Solar declination and hour angle at −18°
Nothing to see from June to July
Through those months the sun never falls more than 18° below the Caerphilly horizon, so the sky never darkens fully. Plan around the darker half of the year.
Getting clear of the light
The sky over Caerphilly reads Bortle 7. Getting clear of the built-up area makes a visible difference on a marginal night.
- 20 km north — around Blaenau Gwent → Bortle 5
- 42 km west-north-west — around Neath Port Talbot → 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, August and November came out ahead in Caerphilly. 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 Caerphilly viewing season.
- 13 Aug 2026
- 11 Sep 2026
- 11 Oct 2026
- 09 Nov 2026
- 09 Dec 2026
- 07 Jan 2027
- 06 Feb 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 Inverness, 660 km north in United Kingdom.
| Caerphilly | Inverness | |
|---|---|---|
| Kp needed | 7 | 5 |
| Nights per year | 2.7 | 28.7 |
| Geomagnetic latitude | 53.9° | 59.8° |
Confirmed reports from this area
53 verified sightings were logged within 300 km of Caerphilly 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 Caerphilly
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 Caerphilly.
- Mynydd Dimlaith — hill3.8 km north
- Mynydd y Grug — hill4.5 km north-north-east
- Mynydd Merthyr — ridge19.1 km north-west
- Mynydd Llangynidr — mountain27.8 km north-north-west
- Craig y Llyn — cliff29.9 km north-west
- Cefnmawr — mountain32.2 km west-north-west
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. Caerphilly keeps its fortified past above ground, at Caerphilly Castle, Gwern y Domen and Castell Meredydd, and for a day when the cloud sits low, St Fagans: National History Museum 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 Caerphilly will do; what matters is being able to step outside and check the sky without a drive first.
- Maes Manor Country Hotel 12.1 km from the centre
- Best Western New House Cntry 3.2 km from the centre
- Best Western Plus New House Co 3.2 km from the centre
- Manor Parc 3.5 km from the centre
- Best Western New House Country Hotel 4.4 km from the centre
- quality 5.3 km from the centre
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 Caerphilly and the sky was dark enough to show it.
| Date | Peak |
|---|---|
| 2026-03-20 | Kp 7.0 |
| 2026-01-20 | Kp 7.67 |
| 2026-01-19 | Kp 8.67 |
| 2025-11-12 | Kp 7.33 |
| 2025-11-11 | Kp 8.67 |
NOAA planetary Kp
Know when it is worth going outside
Revon watches the Caerphilly forecast and pushes an alert when the odds for tonight clear your threshold — no checking, no guessing.
Common questions about the aurora borealis in Caerphilly
Can you see the aurora borealis from Caerphilly?
Yes. On the last 10.0 years of NOAA Kp records, Caerphilly had about 2.7 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 Caerphilly?
Kp 7. Caerphilly sits at geomagnetic latitude 53.9°, and the auroral oval only reaches that far from the pole once activity hits Kp 7. Storms that size occur about 3.2 nights a year.
When is the best time of year to see the aurora borealis in Caerphilly?
September, August and November. Those months scored highest once both conditions are counted together: geomagnetic activity and enough hours of real darkness. From June to July the sky over Caerphilly never gets fully dark, so nothing is visible however strong the storm.
Where can you escape the light pollution near Caerphilly?
The centre of Caerphilly reads Bortle 7. The nearest sky at Bortle 4 is about 42 km west-north-west around Neath Port Talbot. On a marginal night that drive matters more than the forecast does.
Where is the nearest place to Caerphilly with reliable aurora borealis?
Inverness, United Kingdom — 660 km north. It needs only Kp 5 and averages 28.7 viable nights a year against 2.7 in Caerphilly.
Nearby towns
Forecasts for places within reach of Caerphilly.