Mountain weather
Snowdonia Mountain weather forecast table
Confidence
High for an unsettled period through the weekend and into next week. Lower for exact detail on when and where the heaviest showers may develop. Moderate confidence on the timing of rain arriving for Tuesday.
Mountain weather hazards
Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.
Strong Sunlight
Harmful UV levels from sunlight increase with altitude giving a greater risk of sunburn and eye damage, even on some overcast days. On breezy days, the cooling effect of wind on exposed skin may disguise any feeling of sunburn until it is too late. If there is snow cover, glare increases the effect of UV rays especially on the eyes. It is advisable to wear sun block, protective clothing such as a long-sleeved top and hat and have good quality eye protection.
Thunderstorms
Lightning is a significant mountain hazard which can result in serious injury or death. Mountain terrain often leaves one highly exposed to lightning strikes. Hail may give unpleasant conditions with torrential rain and localised flash flooding also possible, mainly in Summer months.
Gales
Gale force winds (gusts over 50mph) make walking difficult and strenuous with a potential to be blown over by gusts. There is often a marked increase in winds through cols or on exposed ridges and summits. Distances can take longer to cover and compass bearings become harder to follow accurately.
Severe Chill Effect
Wind significantly lowers the ‘feels-like’ temperature relative to the actual temperature, with even moderate winds significantly adding to the chilling effect. Strong winds can result in a severe and debilitating wind chill many degrees below the actual temperature. This effect will be enhanced in rain or wet snow. Without protection, prolonged exposure could result in frost nip or frostbite on exposed parts of the body and/or hypothermia.
Poor Visibility
Poor visibility presents challenging route finding conditions. Visibility could be significantly less than 50 metres in all directions with few or no visual references, especially on featureless moors or plateaux. Distances become hard to judge and cliff or cornice edges can be difficult to recognise. These conditions require good navigational skills. There is a risk of white-out conditions when mist or fog is combined with extensive snow cover.
Heavy Persistent Rain
Heavy and persistent rain can lead to drenched clothing and footwear with waterproofs often becoming soaked through, especially if accompanied by strong winds. This can lead to significant loss of body heat and an increased likelihood of hypothermia. Terrain may turn increasingly boggy underfoot while streams can flood and become impassable. There may also be a risk of flooding in valleys or glens. If there is snow cover, a heightened avalanche hazard is possible and avalanche reports should be consulted where available.
Mountain weather forecast
Scattered heavy, possibly thundery, showers and spells of strong sunlight.
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
30% | 40% | 60% | 60% | 40% | 30% |
Wind direction and speed (mph)
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
SW
39
|
S
38
|
S
35
|
S
36
|
S
36
|
S
39
|
| 600m |
S
28
|
S
29
|
S
27
|
S
28
|
S
27
|
S
27
|
| 300m |
S
18
|
S
21
|
S
19
|
S
20
|
S
19
|
S
18
|
| Valley |
S
18
|
S
21
|
S
19
|
S
20
|
S
19
|
S
18
|
Wind gust (mph)
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m | 47 | 47 | 45 | 46 | 46 | 48 |
| 600m | 34 | 37 | 37 | 37 | 37 | 36 |
| 300m | 30 | 34 | 34 | 35 | 34 | 33 |
| Valley | 30 | 34 | 33 | 35 | 34 | 33 |
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
6°
|
6°
|
7°
|
8°
|
7°
|
5°
|
| 600m |
8°
|
8°
|
9°
|
10°
|
9°
|
8°
|
| 300m |
10°
|
12°
|
12°
|
13°
|
12°
|
10°
|
| Valley |
12°
|
13°
|
14°
|
15°
|
14°
|
12°
|
| Freezing Level |
1,700m
|
1,600m
|
1,700m
|
1,600m
|
1,600m
|
1,600m
|
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
-1°
|
0°
|
1°
|
2°
|
1°
|
-1°
|
| 600m |
3°
|
4°
|
5°
|
6°
|
5°
|
3°
|
| 300m |
7°
|
8°
|
9°
|
10°
|
9°
|
7°
|
| Valley |
8°
|
10°
|
10°
|
11°
|
10°
|
9°
|
Additional weather information
Meteorologist's view
Be prepared to quickly change course should any thundery showers develop. It will also feel rather cold on the summits in the strong winds.
Weather
A day of clear/sunny spells and showers. The showers will be most widespread mid-morning to mid-afternoon, and some will be heavy with a risk of thunder. Showers easing off into the evening allowing for some late sunshine, though more widespread cloud beginning to push into the west during the final couple of hours of the day.
Chance of cloud-free hill tops
80%
Low cloud and visibility
Very good visibility for most of the time with distant hills clear to see. However, visibility will quickly deteriorate to poor under any showers. The heaviest showers could also lower the cloud to 850-900m and briefly cover the highest summits.
Ground conditions
Please see - https://www.eryri.llyw.cymru/visiting/walking/ground-conditions
Mountain weather information
Weather
Cloud soon spreading across the park accompanied by showers or longer spells of rain, often heavy and perhaps thundery at times. The showers and rain continuing through the morning and into the afternoon before gradually easing off for the evening.
Chance of cloud-free hill tops
60% for most of the day.
Maximum wind speed expected
35-40mph southerly winds on the summits, gusting 50-55mph at times.
Temperature
- At 800m Plus 4 Celsius, rising to plus 6 Celsius.
- Valley Plus 9 Celsius, rising to plus 18 Celsius.
- Freezing level Above the summits.
Low cloud and visibility
Widespread cloud predominantly around 850-900ft but occasionally lowering to 500-600ft, chiefly on western slopes, shrouding the higher routes. Visibility also dropping at lower levels as a result of any rain, but largely good in between.
Mountain weather information
Mon 27 Jun
Sunrise:
Sunset:
Winds on the hills easing to moderate southwesterlies. A day of scattered showers, sometimes heavy to begin but becoming increasingly light through the afternoon. Sunny spells between the showers. Freezing level above the summits.
Tue 28 Jun
Sunrise:
Sunset:
Cloud quickly arriving first thing with accompanying outbreaks of rain, heavy at times, continuing through the day. Becoming unseasonably windy with strong and gusty southerly winds developing. Freezing level well above the summits.
Wed 29 Jun
Sunrise:
Sunset:
A return to scattered showers, some of which could be heavy. Generally cloudy in between any precipitation to begin but with some bright or sunny spells developing later. Winds easing to moderate southwesterlies. Freezing level remaining above the summits.
Updated at:
Summit specific forecast
Mountain summit forecast map
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Key
Mountain summits
Other points of interest
Cluster of multiple stations
The Snowdonia mountains are made up of 90 mountain peaks including the tallest mountain in Wales, Snowdon, standing at 1,085 metres.
The region can be divided into four areas with the northernmost area the most popular, including peaks such as Moel Hebog, Mynydd Mawr and the Nantlle Ridge. Many hikers tend to concentrate on Snowdon itself regarding it as a fine mountain. However it can become quite crowded, with the peak welcoming around half a million visitors every year, of which four fifths scale the peak on foot, while the remainder choose to take the train instead.
One of Snowdon’s main attractions is the sheer number and variety of paths that reach the peak. This means that everyone from mountaineering novices to climbing experts should find a way up the mountain that will suit their abilities or provide them with a sufficient test. The easiest is the Llanberis path which, being the longest, has the most shallow ascent. In contrast, the Watkin Path is widely seen as being the most demanding ascent, despite also being considered the prettiest.