The end of October 2024 saw several consecutive days of impressive temperature inversions (often incorrectly called ‘cloud inversions’) at the summit of Yr Wyddfa (Snowdon). Being half-term holiday and a period of dry weather, the mountain was busy, and for most people the views at the summit came as a complete surprise; there was thick cloud lower down the mountain which gave way to clear blue skies near the summit.
For many of these people, this was their first experience of such a phenomenon, and one likely never to be forgotten; inversion conditions are also good for seeing Brocken spectres, and many walkers descending on the Llanberis path were witness to this too.
(For info, a Brocken spectre is when your enlarged shadow appears on the cloud below you, and features a rainbow-coloured halo around your head. As with any rainbow, it will appear in the opposite direction to the sun, which is why walkers descending north from the summit are most likely to see one. They rarely come out as well in photos as compared to the naked eye.)
Trains were also running to the summit too, on what were the last days of the season, and these passengers similarly travelled up through the cloud before reaching the blue skies above.
Very few of the people who enjoyed the inversion would have been aware that inversion conditions were around; that wasn’t their reason for being there – and anyway they are notoriously hard to predict – but they were simply in the right place at the right time, and I found myself recalling similar events in the past.
A temperature inversion from the summit. Peaks above about 2500′ were above the clouds.
A couple of years ago the mountain had seen weeks of poor weather throughout August, and in early September, on the day that the weather changed for gorgeous summer weather and summit views, I recall talking to a couple on the Llanberis path. I asked if they’d come that day because they had seen that the weather had finally changed for the better? Not at all! They had been to a car rally event in Ireland, and after crossing back to Holyhead, they had always intended to do a quick ascent of Yr Wyddfa – their first time – before continuing their journey home later that day. They had no idea that this was the first fine day in weeks!
I recall too a winter inversion. This was probably the best temperature inversion I have ever seen, and I found myself talking with a lady at the summit, where we saw a Brocken spectre to the north of us. It turns out that this was the first time that this lady had ever been up Yr Wyddfa, and yet here she was, a witness to one of the best inversions ever, with a Brocken spectre thrown in too.
Another occasion which comes to mind was the group of girls I met on a hen-do. The date had been set months in advance, and none of them had ever walked up Yr Wyddfa before. On this particular day, conditions improved through the morning, and as they reached the summit the last of the cloud burned off to reveal stunningly sharp views in all directions; it was one of those days when Ireland and the Lake District were clearly visible. The day before had been miserable, as was to be the one afterwards; I’m not sure that they ever knew how lucky they were.
Yes, there’s an element of luck in what weather you get on the mountain, especially at the summit, and even experienced walkers can never be certain of what to expect. We all know people who have been up the mountain numerous times but have never had views from the top, and as I’ve just recounted, there are also some very lucky people who just happened to be in the right place at the right time.
I sometimes wonder if some of these lucky people, who experience the mountain in ideal conditions on their one and only visit, think that Yr Wyddfa is always like that!