Snow star crystal 1.5mm diameter grown on an electric needle: Photo Ken Libbrecht. Snow covered Stevenson screen.

Llansadwrn (Anglesey) Weather:
Snowdonia Snowline Report

Logo: Llansadwrn Weather - Melin Llynnon, Ynys Môn.

Snowdonia Mountains Winter Season 2017 - 18

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Current snowline histogram. Snowline histogram


Snow on summits of the Snowdon Horseshoe on 4 January 2010.




There was no snow seen in October. Some ice precipitation was seen on the ground on Cairngorm Mountain on the 29th early in the day'


A sprinkling of ice precipitation was seen again on Cairngorm Mountain on the 2nd with remnants on the 3rd. Snow is forecast for Snowdonia for the 4/5th, that may be a significant amount, as low as 2000 ft. Cloud persisted around the summits all day on the 5th and in the event there was not as much snow as hoped for, but John Williams reported that both Carnedd Dafydd and Carnedd Llewelyn were cold enough to receive snow showers and they left a light sprinkling. Temperatures at 1000 metres hovering between -1 and 0 degrees. Above cloud base at 900 metres/2950 feet there was a light covering of snow at the top of the two summits by early evening. Snow on the Carneddau Mountains. Snow on the NW flank of Snowdon.

Some wintry showers around the summits on the 7th and on the 12th frequent showers of snow pellets at low levels; snow pellets and snow showers left sprinklings above 2250 ft and covering some of the highest summits and Snowdon. There was a good covering seen on the NW flank, and on the Carneddau, when the cloud lifted in the afternoon. After a cold night -5C on on the summit on the morning of the 13th a light covering of snow still remained. There was a little ice precipitation around the summits on the 18th. At 09 GMT on the 23rd there was a sprinkling of snow on Carnedd Llewelyn as low as 2650 ft (810m). The mountains appeared clear of snow on the morning of the 24th then wintry showers developed later. The 25th had a light dusting of snow as low as 1250 ft in places, mainly above 2250 ft in the afternoon. Further showers and flurries on the 26th with light lying snow in places above 2500 ft, with the summit of Snowdon well iced, only to mostly thaw overnight 26/27th in warm sector air. Wintry showers returned on the 27th around the highest summits and later in the day at lower level. Showers continued overnight, mainly wet soft hail (snow pellets) at low levels, with sparse snow and hail lying above 2500 ft, with remnants of hail on the ground as low as 1000 ft in the morning.Snow on Garnedd Ugain, Yr Wyddfa and the railway line.Snow and hail showers continued on the 28th with a little deposited at 1000 ft at Ogwen with light accumulations at higher levels. By the 29th there was a good covering around Snowdon including the PYG track and railway line; on the north-facing Carneddau snow cover was as low as 2000 ft. Derek Brockway and Donald's photo of Snowdon BBC Wales Weather 1850 GMT.Snow was lying at 2250 ft on the Carneddau on the morning of the 30th where snow showers were traversing the Black Ladders area. In the afternoon snow was seen to be covering most of the upper part of the railway line; severe wind chill on the summit -14C with wind gusting 54 mph. The photo left was tweeted to Derek Brockway, the BBC Wales weather presenter, and it was shown as a backdrop to his evening weather forecast (right).



There was snow on the tops on the 1st and was lying at 2500 ft with remnants at 2250 ft. Ice precipitation continued at times on the 2nd and 3rd with varying temperatures and amounts on the ground until the 4th when precipitation was mainly sleet. On the 6th there was no snow seen on the Carneddau, Snowdon was in cloud.

Significant snowfall was forecast for Friday/ Saturday 8/9th. The Met Office issued a yellow warning...mainly Scotland, Northern Ireland and Wales on Friday. 2-5 cm of snow is likely for some, with 10-20 cm possible over high ground... Updated at 1115 GMT on the 6th impact level from low to medium

Snow on the Carneddau Mountains at 1030 GMT. Frequent showers of snow pellets and snow in the evening of the 7th and overnight with deposits as low as 250 ft in places and light accumulations over 2000 ft at 0900 GMTon the 8th. Frequent showers in the morning with further accumulations taking place at higher levels.

Met Office Amber Warning issued 0951 GMT ... Between 04:00 Sun 10th and 18:00 Sun 10th A spell of heavy snow is likely over parts of Wales, the Midlands and parts of Northern England...

An icy Nant Ffrancon Pass, Tryfan & Cwm idwal. On the 9th snow was lying at 450 ft on the N-facing slopes of the Carneddau with light moderate accumulations above 2000 ft. In sub-zero temperatures there was ice as low as 250 ft, or lower, in many places. Heavy snow fell widely over high ground in Wales overnight and on the 10th heavy snow reported including Capel Curig, Bala, Brecon and Sennybridge, light snow at lower levels in Llanfairfechan (2-4 cm) and slight in SE Anglesey; whiteout conditions reported on the mountains. Modis Terra image courtesy of the Rapid response team at LANCE. A fine day on the 11th with little change in the snowline at 450 ft on the Carneddau, almost clear of cloud over Wales the snow cover could be seen on the MODIS Terra satellite image (left). Little change again on the 12th though cloudier with Snowdon obscured. On the 13th snow lying at 2500 ft on the Carneddau remnants at 2000 ft. Further snow by the 14th with lying snow at 2000 ft, some as low as 1500 ft with remnants at 1000 ft. Snow in the early hours with wintry showers continuing on the 15th, lying snow at 2500 ft and 30% cover at 2000 ft with some at 1500 ft. Flurries on the 16th some deep snow patches in areas particularly within the Snowdon Horseshoe, 30% cover above 2000 ft persisting on the N-facing slopes of the Carneddau. Snow was beginning to disappear at lower levels on the 17th as temperatures rose although still cold around the summits. Snow cover was mainly above 2750 ft on the 18th with icy deposits still at 1500 ft. Warmer on the 19th with broken snow thawing at all levels.

Overnight 25/26th fresh snow fell and on the morning of the 26th was lying above 2500 ft on the Carneddau with drifts in places and had settled as low as 2000 ft in places. More snow fell and on the 27th snow was lying above 2250 ft with 30% cover at 1800 ft. On the 28th there were icy remnants in places as low as 250 ft, or lower, with 30% cover above 1800 ft on the Carneddau, light to moderate snow was lying generally at 2250 ft and above, deeper in places in drifts. Snow cover persisted until the 29th then became broken on the 30th and with rain overnight 30/31st some old snow drifts and cornices remained on the 31st with frequent small patches persisting as low as 2250 ft.


On the 1st there were small snow patches some as low as 2250 ft, a few old drifts and cornices in a few places. Wintry showers continued at times and on the 2nd with little accumulation taking place. Ice precipitation showers continued at times around the highest summits on the 3-4th and more overnight 4/5th left light snow lying at 2250 ft on the Carneddau, most NW flank of C. Dafydd at 0900 GMT on the 5th, with sprinklings seen as low as 2000 ft. Snow continued present around the summits 6th to 8th, wintry showers on the 9th with snow on the summits and frost/ ice to low levels. After rain frequent small snow patches with some large at 2750 ft remained on the 10th. Colder on the 12th, Snowdon -7C (chill -15C) at 09 GMT, showers of ice precipitation resumed on the 13th & 14th with 30% cover at 3000 ft. Sleet turning to snow overnight 15/16th left light snow lying above 2500 ft with a 30% cover as low as 2250 ft on the morning of the 16th. Snow at times on the 17th around he summits with little change in levels, but rain overnight 17/18th reduced the cover on the 18th to above 2950 ft. Colder again with snow settling later in the day and on the 19th restored the snowline to 2500 ft with some at 2000 ft on the slopes of the Carneddau and 1250 ft near Ogwen. Fresh snow in the morning of the 20th settled at 1000 ft at Ogwen and the A5 during the day. Warm sector air and rain overnight 21/22nd left only snow patches on the 22nd, large at 2650 ft with remnants of snow at 2250 ft. On the 23rd some snow patches and icy remnants reduced on the 24th in warm rain. Ice precipitation on the 25th gave fresh sprinklings around the summits and as low as 2250 ft in places. Snow overnight 25/26th left light lying at 2750 ft on the 26th and isolated patches and light snow on the 27th above 2850 ft. By the 30th there were icy remnants over 3100 ft on the Carneddau. Early hail and snow showers on the 31st left sprinklings mostly above 3000 ft and as low as 2500 ft on the NW slopes of Garnedd Ugain.


On the 1st snow overnight had left a slight covering above 2000 ft and as low as 1800 ft on the lower slopes of the Carneddau. On the 4th snow lying at 2500 ft and 30% cover as low as 2000 ft. On the 5th a band of snow encroached early in the morning and brought snow to low levels including Anglesey and parts of Llyn with moderate falls above 1000 ft on the mountains. On the 6th snow fell at low levels in the morning with moderate falls over 1000 ft. Further snow fell on the morning of the 7th, again at low levels with the area around Llyn Ogwen well covered. On the 8th temperatures rose during the day with snow thawing at lower levels. The 10th saw warm rainfall with rapid thaw in the afternoon at all levels before temperatures fell again overnight. There were fresh dustings of snow and snow pellets on the morning of the 11th as low as 2250 ft on the Carneddau and elsewhere. On the 13th a band of rain turning to sleet then snow moved across from the WNW in the morning with snow settling and lying at 650 ft and light to moderate falls over 1000 ft. The 14th was very windy with snow showers generally over 1000 ft. From the 15th broken snow areas persisted along with frequent old drifts, frozen ground and hard snow. Areas of snow on the tops of the Carneddau including Foel-fras on the 17th with some snow filled north-facing gullies persisting with remnants as low as 1800 ft in places. Llyn Ogwen frozen over. Photo courtesy of the North Wales Police. By the 19th snow had reduced in places, but areas of snow with frequent snow patches and old drifts remained on the 21st on the Carneddau and Snowdon with streams and wet area frozen. Frequent snow patches were persisting as low as 2250 ft on the 23rd as wet area and streams at higher levels remained frozen. Remnant snow areas and patches remained on the 26th above 2500 ft with snow lying at 2100 ft. On the 27th early heavy snow showers across North Wales brought snow lying to all levels including Anglesey. By the 28th several lakes had frozen over including Llyn Ogwen (Photo courtesy of the North Wales Police @NWPBangor).


On the 1st snow was lying generally above 500 ft with remnants as low as 250 ft in places. In sub zero temperatures flurries of ice precipitation continued through the day at all levels and at times on the 2nd with little change in altitude on the 3rd. On the 4th there was a thaw at low levels raising the snowline to 2750 ft leaving remnants as low as 250 ft, but temperatures were still below zero on the summits and snow showers continued to accumulate. Further snow showers on the summits on the 5th early and late in the day, frequent old drifts remain on the lower slopes of the Carneddau with remnants at 250 ft. Fresh light snow above 2500 ft on the 6th topped up again on the 7th above 2500 ft. Early on the 8th an occluded front moved in from the west bringing at first rain then turning to snow with between 2 Snow lying on section of the Carneddau afternoon of the 19th March 2018. and 7 cm in places and at sea level across Anglesey with moderate accumulations taking place on the mountains. On the 9th snow was lying above 1800 ft, on the north-facing Carneddau with large old drifts persisting below, rising to 2500 ft on the morning of the 10th as overnight tropical air had brought rising temperatures and rain leading to a thaw at all altitudes. There were snow patches persisting at 2000 ft. The lowest snow patches seen from the 12th were at 2500 ft. On the 18th light to moderate snow fell as low as sea level across much of North Wales early in the day and there was still a light covering on the morning of the 19th above 450 ft. There was a thin covering of lying snow on the 20th above 2000 ft with a 30% cover above 1500 ft on the north-facing slopes of the Carneddau. There were patches of snow and remnants of snow drifts along roadside and field hedges as low as 250 ft in places. Fresh light snowfall on the Carneddau afternoon of the 28th March 2018. On the 21st a sprinkling of fresh snow seen on the summits of Carnedd Llewelyn, C. Dafydd and Glyders, the 50% snowline had risen to 2950 ft. Icy conditions and old snow drifts persist above 1500 ft with remnants of snow seen at 250 ft. By the 23rd snow patches remained at 1800 ft rising to 2000 ft on the 27th. On the 28th fresh snow fell by afternoon settling above 2000 ft and remained lying at that altitude from the 29th to the end of the month.


Snow cover on Carnedd Llewelyn on 1 April 2018. On the 1st snow was lying above 2000 ft on the Carneddau with fresh snow added overnight. Before and after midnight on the 2nd more snow fell on the summits and at lower levels rain turned to snow with heavy snow at Ogwen (A5) at 1000 ft in the morning and wet snow at lower levels in places quickly thawing. Rain on the 3rd thawed some snow, but left frequent lines of large old snow drifts as low as 2250 ft and >50% cover above 2500 ft. A fresh fall of snow left sprinklings as low as 1800 ft early in the morning of the 5th with snow lying above 2500 ft. On the 6th there was >50% broken snow above 2750 ft snow patches as low ae 2250 ft on the slopes of the Carneddau. On the 26th there was a fresh sprinkling of snow on the peaks over 3100 ft and again on the 27th and 28th and there was still a little remaining on the 30th.

Snow patches remained on the north-facing Carneddau and Snowdon until the end of the month, but south-facing Y Foes Ddyfn (The Deep Cut) on Carnedd Llewelyn that had a good amount of snow in it on the 19th was empty before the end of the month.


A fresh sprinkling of snow on Yr Wyddfa and G. Ugain on 2 May 2018.There were snow patches surviving on the 1st despite rain within the Snowdon Horseshoe largest on Y Lliwedd, and on the north-facing C. Llewelyn above Cwm Bychan and cliffs of Ysgolion Duon. On the 2nd after frontal clearance the temperature dropped and there was a fresh sprinkling of snow seen on the summits of Yr Wyddfa, Garnedd Ugain, Penyrole Wen, Carnedd Dafydd and C. Llewelyn in the afternoon as the cloud lifted. By the 5th monitored snow patches had all melted.

Snowdonia snowline histogram season 2017-18.


  • You can view the snowline histograms for previous years here:

  • Winter 2016-2017. Winter 2016-2017
    Winter 2015-2016.  Winter 2015-2016
    Winter 2014-2015. Winter 2014-2015

  • You can view complete snowline reports for previous years here:

  • Winter 2016-2017. Winter 2016-2017
    Winter 2015-2016. Winter 2015-2016
    Winter 2014-2015. Winter 2014-2015

  • For earlier archived reports refer to the Site Map.



    Observations were made as near to 0900 GMT as possible. I have a good view from Llansadwrn, weather permitting, across the Menai Strait towards the Snowdonia Mountains. I can see the northern slopes of the mountain range from Moel Eilio (west of Snowdon), Snowdon summits (Yr Wyddfa and Crib Goch), the Glyderau and Carneddau to Foel-fras and Drum to the east of the range near the Conwy Valley. With the aid of binoculars I made daily records that include any ice precipitation observed, the lowest altitude of snow lying at ( >= 50% cover), at ( >= 30% cover) and snow patches.

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    Page first published 31 August 2017, page now archived

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