Rare Noctilucent Visible in Irish Skies

Ireland has been treated to a rare sight in recent nights — shimmering, electric-blue clouds, known as noctilucent clouds, rippling across the twilight sky.

These ghostly formations are the highest clouds in Earth’s atmosphere and are rarely seen at Irish latitudes.

Appearing long after sunset, typically between 60 and 90 minutes after the sun dips below the horizon, noctilucent clouds glow with a silvery-blue hue and often display delicate wave-like patterns. Their sudden appearance over Ireland this week has sparked widespread excitement — and questions.

What Are Noctilucent Clouds?

Noctilucent clouds, meaning “night-shining” clouds, form in the mesosphere, around 76 to 85 kilometres above the Earth’s surface — much higher than any weather-related clouds. They are made of tiny ice crystals, which catch the sunlight from below the horizon and scatter it, creating their ethereal glow.

Because they form in such thin, dry air at the edge of space, these clouds are usually visible only during summer months and typically at higher latitudes, such as Scandinavia, Canada, or northern Russia. Seeing them over Ireland is relatively rare — and always striking.

Why Are We Seeing Them Now?

Their appearance over Irish skies in late June is linked to a combination of seasonal and atmospheric conditions:

• Summer Sunlight Geometry: In summer, the sun sets at a shallow angle, allowing its rays to illuminate the mesosphere long after the surface is in darkness. This is what makes the clouds visible.
• Cold Temperatures in the Upper Atmosphere: Despite summer warmth at the surface, the mesosphere becomes extremely cold — below -120°C — which is ideal for forming ice crystals.
• Increased Water Vapour and Dust: Scientists believe that rising levels of water vapour in the upper atmosphere — possibly linked to climate change or increased rocket launches — may be contributing to the frequency and brightness of noctilucent clouds. The ice forms on tiny dust particles, which can originate from micrometeoroids or even human activity.

This year, atmospheric scientists have noted above-average noctilucent cloud activity, with sightings reported as far south as central France and now over much of Ireland. Social media has lit up with photos from Cork to Donegal, showing glowing cloud bands stretching across the twilight sky.

While noctilucent clouds are breathtaking, some researchers suggest their increasing frequency and southern reach could be a subtle sign of changing atmospheric dynamics — including the cooling of the mesosphere and shifts in global circulation patterns.

When and Where to See Them

To catch a glimpse:

• Look north or northwest, 60 to 90 minutes after sunset or before sunrise.
• Seek a location with a clear view of the horizon and minimal light pollution.
• Bring a camera — noctilucent clouds often show up better in photos than with the naked eye.

With clear skies forecast for many parts of the country up to and including Wednesday night, more sightings may be on the way.