Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High confidence for overall themes, lower for shower detail on Saturday.
Mountain weather hazards
Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.
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.
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.
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.
Mountain weather forecast
Cloudy with some bright spells, risk of showers, perhaps heavy with a risk of thunder.
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
20% | 60% | 40% | 10% | 10% | <05% |
Wind direction and speed (mph)
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
SW
19
|
SW
16
|
SW
16
|
SW
14
|
W
9
|
SW
6
|
| 600m |
SW
13
|
SW
13
|
SW
12
|
SW
12
|
W
8
|
S
6
|
| 300m |
SW
8
|
SW
9
|
SW
9
|
SW
9
|
W
5
|
S
3
|
| Valley |
SW
8
|
SW
8
|
SW
8
|
SW
8
|
NW
6
|
S
3
|
Wind gust (mph)
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m | 23 | 22 | 22 | 19 | 13 | 7 |
| 600m | 17 | 18 | 18 | 17 | 11 | 8 |
| 300m | 14 | 15 | 16 | 15 | 9 | 5 |
| Valley | 14 | 14 | 15 | 14 | 10 | 5 |
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
8°
|
8°
|
9°
|
10°
|
10°
|
9°
|
| 600m |
10°
|
10°
|
11°
|
12°
|
12°
|
11°
|
| 300m |
12°
|
13°
|
14°
|
14°
|
15°
|
13°
|
| Valley |
14°
|
14°
|
15°
|
16°
|
16°
|
13°
|
| Freezing Level |
2,000m
|
2,300m
|
2,300m
|
2,300m
|
2,300m
|
2,300m
|
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
3°
|
4°
|
6°
|
7°
|
8°
|
8°
|
| 600m |
7°
|
8°
|
9°
|
10°
|
11°
|
10°
|
| 300m |
11°
|
11°
|
12°
|
13°
|
14°
|
12°
|
| Valley |
12°
|
13°
|
14°
|
15°
|
15°
|
13°
|
Additional weather information
Meteorologist's view
Heavy showers may cause some localised surface water flooding, care should be taken underfoot. Despite largely cloudy conditions, UV is still likely to be high with appropriate sun protection advised.
Weather
Cloud will be increasing from the west this morning, with a band of organised showers moving northeast, the showers may be heavy with a risk of thunder. This band clears east by the afternoon and turns brighter with sunny spells behind, although still a risk of the odd isolated shower. Skies clearing and showers easing by the evening.
Chance of cloud-free hill tops
30% in the west, 70% in the east at first becoming 80% by the afternoon and greater than 95% in the evening.
Low cloud and visibility
Scattered cloud obscuring western hills above 300-400m at first, clearer in the east with cloud filling in and thickening from the west during the morning. Bases generally above summits by mid to late morning but cloud bases dropping to 700-800m in any showers. Poor visibility in the west at first, becoming good or very good, falling to poor in heavy showers.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Isolated patches of mist and fog in the low valleys around dawn, quickly clearing to see a fine day across the Park with plenty of sunshine. High UV levels are expected.
Chance of cloud-free hill tops
Greater than 95%.
Maximum wind speed expected
Southerly 10-15mph gusting 20mph.
Temperature
- At 800m Plus 6 Celsius becoming Plus 14 Celsius.
- Valley Plus 9 Celsius becoming Plus 22 Celsius.
- Freezing level Above summits.
Low cloud and visibility
Mist and fog in the low valleys around dawn bringing some poor or very poor visibilities to start, but summits remaining clear, any patches of mist or fog quickly burns away leaving good or very good visibilities for much of the day.
Mountain weather information
Mon 29 Jul
Sunrise:
Sunset:
Mist and isolated foggy patches in the valleys, clearing quickly to see a fine and dry day with plenty of sunshine. High UV. Gentle to Moderate southerly.
Tue 30 Jul
Sunrise:
Sunset:
Another day of sunny spells with high UV levels. Gentle to Moderate southerly becoming northwesterly winds.
Wed 31 Jul
Sunrise:
Sunset:
Settled weather continues with a good deal of sunshine persisting. High UV. Light and variable winds.
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 Eryri (Snowdonia) mountains are made up of 90 mountain peaks including the tallest mountain in Wales, Yr Wyddfa (Snowdon), standing at 1,085 metres.