Aurora Borealis in Merthyr Tydfil
United Kingdom · 51.75°, -3.38° · geomagnetic 54.1° · needs Kp 7
Tonight in Merthyr Tydfil
6%
Peak chance of a visible display tonight, from the same model the Revon app runs. Merthyr Tydfil 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 Merthyr Tydfil
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 Merthyr Tydfil 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 Merthyr Tydfil
Revon aurora model over the NOAA Kp forecast and 27-day outlook
How often the aurora borealis reaches Merthyr Tydfil
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, Merthyr Tydfil 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 | 2.1 | 0.0 | 0.0 | 4.6 | 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 Merthyr Tydfil horizon, so the sky never darkens fully. Plan around the darker half of the year.
Getting clear of the light
The sky over Merthyr Tydfil reads Bortle 5. Getting clear of the built-up area makes a visible difference on a marginal night.
- 8 km west — around Rhondda Cynon Taf → Bortle 5
- 26 km 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 Merthyr Tydfil. 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 Merthyr Tydfil 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, 640 km north in United Kingdom.
| Merthyr Tydfil | Inverness | |
|---|---|---|
| Kp needed | 7 | 5 |
| Nights per year | 2.7 | 28.7 |
| Geomagnetic latitude | 54.1° | 59.8° |
Confirmed reports from this area
56 verified sightings were logged within 300 km of Merthyr Tydfil 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 Merthyr Tydfil
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 Merthyr Tydfil.
- Morlais Hill — hill3.2 km north
- Twyn y Waun — hill3.5 km east
- Mynydd Llangynidr — mountain8.7 km north-north-east
- Brecon Beacons National Park — park15.1 km north
- Pen y Fan — mountain15.7 km north-north-west
- Cantref Adventure Farm and Riding Centre — park19.5 km north
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. Merthyr Tydfil keeps its fortified past above ground, at Morlais Castle, Madocs Castle and Cae Burdydd Castle.
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)
The last nights it was visible here
Nights in the last decade when the storm was strong enough for Merthyr Tydfil 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 Merthyr Tydfil forecast and pushes an alert when the odds for tonight clear your threshold — no checking, no guessing.
Common questions about the aurora borealis in Merthyr Tydfil
Can you see the aurora borealis from Merthyr Tydfil?
Yes. On the last 10.0 years of NOAA Kp records, Merthyr Tydfil 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 Merthyr Tydfil?
Kp 7. Merthyr Tydfil sits at geomagnetic latitude 54.1°, 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 Merthyr Tydfil?
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 Merthyr Tydfil never gets fully dark, so nothing is visible however strong the storm.
Where can you escape the light pollution near Merthyr Tydfil?
The centre of Merthyr Tydfil reads Bortle 5. The nearest sky at Bortle 4 is about 26 km west around Neath Port Talbot. On a marginal night that drive matters more than the forecast does.
Where is the nearest place to Merthyr Tydfil with reliable aurora borealis?
Inverness, United Kingdom — 640 km north. It needs only Kp 5 and averages 28.7 viable nights a year against 2.7 in Merthyr Tydfil.
Nearby towns
Forecasts for places within reach of Merthyr Tydfil.