*Cofnodi tywydd anarferol (yn hanesyddol).
[[File:Graffiti ym Mhen y Garret, Llanberis yn cofnodi tywydd anarferol.png|thumb|Graffiti ym Mhen y Garret, Llanberis yn cofnodi tywydd anarferol]]
Tynnodd Steve Roddick y llun hwn o graffiti gan chwarelwr ar wal Pen y Garret, chwarel Dinorwig yn cofnodi eira ar yr Wyddfa ym mis Mehefin. Wyddoch chi am eira anhymhorol yng Nghymru? Meddai Huw Holland Jones: The weather map for 13 June 1956 shows a NW airstream right from north of Iceland. I would think therefore the report of snow on Snowdon to be genuine. By the way, 11th June 1956 saw the heaviest 2 hour rainfall ever recorded in Britain, 155mm in 2 hours at Hewenden reservoir, near Halifax W Yorks. The depression that caused such intense rain moved east on the 12 and 13 June, allowing the cold air from the arctic regions to flood across Britain. Snow on our hills in the first 2 weeks of June was not unusual pre- the 1980's. I remember a deep snow cover on the Carneddau, Glyderau & Wyddfa in early June. And of course the famous outbreak of snow across all of Britain, right down to low lying ground, on June 2 1975, is famous.