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Rule Fog Hunter

Llyn Padarn - Fog Hunter - Snowdonia (Eryri)

Llanberis, Wales, United Kingdom

Thick, moody fog for atmospheric forest and landscape shots

Currently

Real-time conditions
Fog Probability
0%
Dewpoint Spread4.8°C
Visibility22527 (Clear)
Relative Humidity73%
Wind Speed7.0m/s (moderate winds)

Upcoming Opportunities

When all conditions match, PhotoWeather marks an opportunity window.

Times shown in Europe/London
fog weather icon
Next opportunity
Dense Fog
Llyn Padarn
Fri, Jun 12 · 16:00–20:00 · 4h window
Low confidence
32%
🌫️Fog Probability77.9-95.3%
Dewpoint Spread: 0.1°C
Visibility: 571 (Fog)
Relative Humidity: 99%
Wind Speed: 2.2m/s (calm conditions)
fog weather icon
Dense Fog at Sunset
Llyn Padarn
Fri, Jun 12 · 20:00–23:00
🌫️Fog Probability:88.6%
Medium

What this forecast looks for

Plain-language explanation from the rule

This forecast tracks when valley inversions and mountain mist create atmospheric conditions for photography in Snowdonia's glacial valleys. We monitor temperature inversions, humidity patterns, and wind conditions to predict optimal fog photography opportunities.

Snowdonia's deep glacial valleys—Nant Gwynant, Llanberis Pass, and Ogwen Valley—act as natural fog bowls where cold air settles overnight, creating spectacular valley inversions with mountain peaks rising through cloud seas. The region's high rainfall and numerous lakes add moisture to the atmosphere, producing frequent mist conditions that transform slate landscapes and mountain tarns into ethereal scenes.

What makes Snowdonia fog photography distinctive:

  • Valley inversions - Nant Gwynant and Ogwen Valley trap cold air, creating cloud seas with peaks emerging above
  • Lake mist - Llyn Padarn and Llyn Ogwen generate morning mist that drifts across mirror-still water
  • Slate atmosphere - Historic slate quarries at Llanberis create moody industrial landscapes in fog
  • Glacial cwms - Cwm Idwal's enclosed cirque traps mist, creating atmospheric waterfall scenes at Devil's Kitchen

The most reliable fog conditions occur during settled high-pressure periods in autumn and winter (September-February) when clear skies allow overnight cooling to create temperature inversions. Nant Gwynant valley is particularly prone to inversions—position yourself at higher viewpoints like Pen-y-Gwryd or along the A498 to capture peaks rising through cloud. Llyn Padarn generates morning mist that drifts past Dolbadarn Castle's tower, creating atmospheric castle scenes. Cwm Idwal's enclosed glacial bowl traps mist against the dramatic headwall of Devil's Kitchen. The timing is critical—arrive before dawn as mist typically burns off within an hour or two of sunrise. Wales's wet climate means fog is common, but our forecast identifies the photogenic conditions when visibility is just right—not too thick to lose definition, not too thin to lack atmosphere.

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72-hour requirements breakdown

What passed or failed, hour by hour
0matching hours in the next 81 hours
AND logic: all conditions required
Meets requirement
Misses requirement
Time
Europe/London
Fog Probability
≥ 75.0%
Mon, Jun 8
05:000%
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Tue, Jun 9
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Wed, Jun 10
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Thu, Jun 11
24:000%
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How to read: colored cells show whether each predicate requirement is met; highlighted rows mean the full rule matched (an opportunity).

What does Fog Probability mean?

Inputs that drive the score

This derived score summarizes multiple raw weather signals. The table below shows the supporting inputs hour by hour, so you can see what's pushing the score up or down.

Time
Europe/London
Clear Sky Probability (Ensemble)
%
Dew Point
°C
Rainfall
mm
Relative Humidity
%
Snowfall
cm
Solar Elevation
°
Temperature
°C
Total Precipitation
mm
Vapor Pressure Deficit
kPa
Visibility
m
Wind Gusts
m/s
Wind Speed
m/s
Mon, Jun 8 Sunrise 04:51 Sunset 21:39
16:00
98% 7.3°C 0mm 73% 0cm 47° 12°C 0.06mm 0.38kPa 22527m 7.7m/s 7m/s
17:00
91% 7.7°C 0mm 77% 0cm 38° 12°C 0.19mm 0.32kPa 16483m 8m/s 7m/s
18:00
85% 8.2°C 0mm 81% 0cm 29° 11°C 0.44mm 0.25kPa 18225m 8.7m/s 7m/s
19:00
78% 8.7°C 0mm 87% 0cm 20° 11°C 0.81mm 0.17kPa 13546m 9.1m/s 6.3m/s
20:00
54% 8.5°C 0mm 89% 0cm 12° 10°C 0.63mm 0.14kPa 9114m 9.7m/s 6m/s
21:00
30% 7.9°C 0mm 88% 0cm 4.1° 9.8°C 1.6mm 0.14kPa 9164m 11m/s 6.4m/s
22:00 ☾
6% 8°C 0mm 89% 0cm -2.9° 9.7°C 2.6mm 0.13kPa 7631m 10m/s 5.6m/s
23:00 ☾
4% 7.8°C 0mm 88% 0cm -8.4° 9.7°C 3.8mm 0.15kPa 6787m 10m/s 6m/s
Tue, Jun 9 Sunrise 04:51 Sunset 21:39
24:00 ☾
2% 7.4°C 0mm 88% 0cm -12° 9.3°C 4.4mm 0.14kPa 11599m 10m/s 4.9m/s
01:00 ☾
0% 7°C 0mm 90% 0cm -14° 8.6°C 4.8mm 0.11kPa 18464m 9.5m/s 4m/s
02:00 ☾
1% 7.2°C 0mm 91% 0cm -13° 8.5°C 0.56mm 0.1kPa 11068m 9.7m/s 4.5m/s
03:00 ☾
1% 7.3°C 0.01mm 91% 0cm -11° 8.7°C 1.2mm 0.1kPa 13026m 10m/s 6.5m/s
04:00 ☾
2% 6.7°C 0mm 93% 0cm -6° 7.8°C 1.5mm 0.08kPa 20835m 9.4m/s 4.9m/s
05:00
1% 6.2°C 0mm 93% 0cm 0.63° 7.3°C 1.8mm 0.07kPa 13118m 8.5m/s 3.9m/s
06:00
1% 6.5°C 0mm 91% 0cm 7.7° 7.9°C 2.1mm 0.09kPa 23491m 9.4m/s 5.1m/s
07:00
0% 7°C 0mm 90% 0cm 16° 8.5°C 2.4mm 0.11kPa 14965m 9.5m/s 6.2m/s
08:00
10% 7.6°C 0mm 89% 0cm 25° 9.3°C 0.38mm 0.13kPa 16189m 9.7m/s 6.9m/s
09:00
20% 7.7°C 0mm 88% 0cm 34° 9.6°C 0.75mm 0.14kPa 16398m 9.7m/s 7.4m/s
10:00
30% 7.8°C 0mm 86% 0cm 42° 10°C 1mm 0.18kPa 18448m 9.4m/s 7.8m/s
11:00
26% 7.7°C 0mm 84% 0cm 50° 10°C 1.2mm 0.21kPa 15795m 9.7m/s 8.2m/s
12:00
23% 7.7°C 0mm 82% 0cm 57° 11°C 1.5mm 0.23kPa 12769m 10m/s 8.3m/s
13:00
19% 7.7°C 0mm 80% 0cm 60° 11°C 1.9mm 0.26kPa 16302m 11m/s 8.6m/s
14:00
31% 7.7°C 0mm 78% 0cm 59° 11°C 0.38mm 0.3kPa 15294m 11m/s 8.4m/s
15:00
44% 7.5°C 0mm 74% 0cm 54° 12°C 0.69mm 0.36kPa 17862m 11m/s 7.9m/s
16:00
56% 7.5°C 0mm 72% 0cm 47° 12°C 1mm 0.4kPa 21201m 11m/s 7.7m/s
17:00
56% 7.9°C 0mm 74% 0cm 38° 13°C 1.3mm 0.38kPa 18821m 9.8m/s 7.2m/s
18:00
56% 8.7°C 0mm 78% 0cm 29° 12°C 1.6mm 0.31kPa 15169m 9.3m/s 6.7m/s
19:00
56% 8.4°C 0mm 80% 0cm 21° 12°C 1.9mm 0.27kPa 16835m 8.4m/s 5.4m/s
20:00
46% 7.9°C 0mm 82% 0cm 12° 11°C 0.31mm 0.23kPa 19579m 8.4m/s 4.4m/s
21:00
35% 7.1°C 0mm 84% 0cm 4.2° 9.6°C 0.56mm 0.19kPa 23368m 8.7m/s 4m/s
22:00 ☾
25% 6.2°C 0mm 87% 0cm -2.8° 8.3°C 0.69mm 0.15kPa 24051m 5.2m/s 3.2m/s
23:00 ☾
19% 6.4°C 0mm 87% 0cm -8.3° 8.4°C 0.88mm 0.14kPa 22851m 4.6m/s 2.6m/s
Wed, Jun 10 Sunrise 04:51 Sunset 21:40
24:00 ☾
12% 6.9°C 0.02mm 87% 0cm -12° 9°C 1.1mm 0.15kPa 23634m 7.8m/s 3.2m/s
01:00 ☾
6% 7°C 0.09mm 88% 0cm -14° 8.8°C 1.4mm 0.13kPa 20454m 5.8m/s 3m/s
02:00 ☾
4% 6.7°C 0.01mm 88% 0cm -13° 8.6°C 0.19mm 0.14kPa 24134m 3.5m/s 2.4m/s
03:00 ☾
3% 6°C 0mm 90% 0cm -11° 7.5°C 0.38mm 0.1kPa 22814m 3.5m/s 2.6m/s
04:00 ☾
1% 5.6°C 0mm 92% 0cm -5.9° 6.8°C 0.69mm 0.08kPa 24134m 4.4m/s 2.9m/s
05:00
1% 5.4°C 0mm 92% 0cm 0.67° 6.6°C 0.88mm 0.08kPa 22347m 4.2m/s 2.8m/s
06:00
0% 6.1°C 0.01mm 92% 0cm 7.8° 7.3°C 1mm 0.08kPa 23595m 3.9m/s 2.6m/s
07:00
0% 7.3°C 0mm 92% 0cm 16° 8.6°C 1.3mm 0.09kPa 19450m 6.6m/s 3.3m/s
08:00
2% 7.5°C 0mm 87% 0cm 25° 9.6°C 0.38mm 0.16kPa 12954m 6.5m/s 3.7m/s
09:00
3% 7.7°C 0mm 86% 0cm 34° 10°C 0.69mm 0.17kPa 20449m 7.6m/s 5.8m/s
10:00
5% 7.5°C 0mm 82% 0cm 42° 10°C 0.88mm 0.23kPa 20335m 7.1m/s 5.2m/s
11:00
4% 7.3°C 0mm 78% 0cm 50° 11°C 1.1mm 0.29kPa 19254m 7.5m/s 5.8m/s
12:00
3% 7.9°C 0mm 79% 0cm 57° 11°C 1.3mm 0.28kPa 16953m 8.2m/s 6.7m/s
13:00
2% 8.2°C 0mm 78% 0cm 60° 12°C 1.6mm 0.3kPa 14882m 8.4m/s 7m/s
14:00
9% 8.2°C 0mm 75% 0cm 59° 12°C 0.19mm 0.36kPa 19817m 8.1m/s 6.8m/s
15:00
17% 8.1°C 0mm 74% 0cm 54° 13°C 0.38mm 0.38kPa 16945m 7.9m/s 6.6m/s
16:00
24% 8.5°C 0mm 76% 0cm 47° 13°C 0.63mm 0.34kPa 15419m 8.2m/s 6.8m/s
17:00
21% 8.7°C 0mm 78% 0cm 38° 13°C 0.88mm 0.32kPa 16499m 7.9m/s 6.5m/s
18:00
19% 8.8°C 0mm 78% 0cm 30° 13°C 1.1mm 0.32kPa 20998m 7.2m/s 5.4m/s
19:00
16% 9.2°C 0mm 82% 0cm 21° 12°C 1.3mm 0.26kPa 17301m 6.5m/s 4.2m/s
20:00
19% 9.2°C 0mm 84% 0cm 12° 12°C 0.13mm 0.22kPa 24135m 5.4m/s 2.3m/s
21:00
21% 7.7°C 0mm 84% 0cm 4.3° 10°C 0.19mm 0.21kPa 24134m 1.8m/s 1.8m/s
22:00 ☾
24% 7.1°C 0mm 85% 0cm -2.7° 9.5°C 0.25mm 0.17kPa 24135m 1.5m/s 1.4m/s
23:00 ☾
21% 7.1°C 0mm 85% 0cm -8.3° 9.6°C 0.25mm 0.18kPa 24135m 1.2m/s 1.1m/s
Thu, Jun 11 Sunrise 04:51 Sunset 21:41
24:00 ☾
17% 6.8°C 0mm 86% 0cm -12° 9°C 0.25mm 0.16kPa 24134m 2.3m/s 2m/s
01:00 ☾
14% 7.3°C 0mm 89% 0cm -14° 9°C 0.25mm 0.12kPa 24134m 2.7m/s 2.2m/s
02:00 ☾
11% 8.1°C 0.64mm 92% 0cm -13° 9.3°C 2.1mm 0.09kPa 16142m 6.5m/s 3.2m/s
03:00 ☾
7% 9°C 1.3mm 95% 0cm -11° 9.7°C 4mm 0.05kPa 8150m 10m/s 4.3m/s
04:00 ☾
4% 9.9°C 1.9mm 99% 0cm -5.9° 10°C 5.9mm 0.02kPa 159m 14m/s 5.4m/s
05:00
3% 11°C 1.9mm 99% 0cm 0.71° 11°C 7.6mm 0.02kPa 139m 12m/s 4.7m/s
06:00
2% 11°C 2mm 99% 0cm 7.8° 11°C 9.2mm 0.01kPa 120m 11m/s 4.1m/s
07:00
1% 12°C 2mm 99% 0cm 16° 12°C 11mm 0.01kPa 100m 9m/s 3.4m/s
08:00
1% 12°C 1.4mm 99% 0cm 25° 12°C 7.8mm 0.02kPa 105m 10m/s 4.2m/s
09:00
0% 13°C 0.74mm 99% 0cm 34° 13°C 4.8mm 0.02kPa 111m 11m/s 5m/s
10:00
0% 13°C 0.12mm 98% 0cm 43° 13°C 1.8mm 0.03kPa 116m 12m/s 5.7m/s
11:00
0% 13°C 0.1mm 96% 0cm 50° 13°C 1.9mm 0.07kPa 7580m 12m/s 5.7m/s
12:00
0% 13°C 0.07mm 93% 0cm 57° 14°C 1.9mm 0.11kPa 15045m 12m/s 5.7m/s
13:00
0% 13°C 0.05mm 90% 0cm 60° 14°C 2mm 0.16kPa 22510m 12m/s 5.7m/s
14:00
0% 12°C 0.04mm 90% 0cm 59° 13°C 1.4mm 0.15kPa 23052m 11m/s 5m/s
15:00
0% 11°C 0.02mm 90% 0cm 54° 13°C 0.75mm 0.14kPa 23593m 11m/s 4.3m/s
How to read: these inputs help produce the derived score; they are not requirements by themselves.

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