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Rule Fog Hunter

Rhinog Fawr - Fog Hunter - Snowdonia (Eryri)

Harlech, Wales, United Kingdom

Thick, moody fog for atmospheric forest and landscape shots

Currently

Real-time conditions
Dewpoint Spread0.3°C
Visibility690 (Fog)
Relative Humidity98%
Wind Speed5.4m/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 at Sunset
Rhinog Fawr
Fri, Jun 12 · 21:00–23:00 · 2h window
Medium confidence
43%
🌫️Fog Probability79.7-91.1%
Dewpoint Spread: 0.2°C
Visibility: 5278 (Moderate)
Relative Humidity: 99%
Wind Speed: 1.8m/s (calm conditions)
fog weather icon
Dense Fog
Rhinog Fawr
Fri, Jun 12 · 23:00–24:00
🌫️Fog Probability:86%
Medium
fog weather icon
Dense Fog at Sunset
Rhinog Fawr
Tue, Jun 16 · 21:00–23:00
🌫️Fog Probability:79.7-100%
Medium
fog weather icon
Moderate Fog
Rhinog Fawr
Tue, Jun 16 · 23:00–24:00
🌫️Fog Probability:77.1%
Low

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 95 hours
AND logic: all conditions required
Meets requirement
Misses requirement
Time
Europe/London
Fog Probability
≥ 75.0%
Sun, Jun 7
03:000%
04:000%
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06:000%
07:000%
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Mon, Jun 8
24:000%
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Tue, Jun 9
24:000%
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Wed, Jun 10
24:000%
01:000%
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19:0048%
20:0030%
21:0043%
22:0049%
23:000%
Thu, Jun 11
24:000%
01:000%
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 04:53 Sunset 21:38
03:00
0% 11°C 7mm 98% 0cm -11° 11°C 7.8mm 0.03kPa 690m 8.2m/s 5.4m/s
04:00
0% 9.8°C 0.34mm 96% 0cm -6.2° 10°C 9.9mm 0.05kPa 5918m 8.7m/s 3.2m/s
05:00
0% 9.5°C 0.32mm 96% 0cm 0.45° 10°C 11mm 0.05kPa 3155m 6.4m/s 3.9m/s
06:00
0% 8.2°C 0.15mm 92% 0cm 7.6° 9.4°C 11mm 0.09kPa 24104m 4.8m/s 2.8m/s
07:00
0% 8°C 0mm 90% 0cm 16° 9.5°C 11mm 0.11kPa 21931m 3.4m/s 2m/s
08:00
6% 8°C 0mm 86% 0cm 25° 10°C 0.13mm 0.18kPa 21418m 4.1m/s 2.7m/s
09:00
11% 7.9°C 0mm 83% 0cm 34° 11°C 0.31mm 0.21kPa 24135m 4.9m/s 3.3m/s
10:00
17% 7.7°C 0mm 82% 0cm 43° 11°C 0.63mm 0.23kPa 17535m 4.9m/s 4m/s
11:00
21% 7.3°C 0mm 78% 0cm 51° 11°C 1mm 0.28kPa 21710m 5.2m/s 4.3m/s
12:00
25% 6.6°C 0mm 73% 0cm 57° 11°C 1.2mm 0.36kPa 24135m 5.7m/s 4.6m/s
13:00
29% 5.7°C 0mm 67% 0cm 60° 12°C 1.2mm 0.46kPa 24134m 6.3m/s 5.2m/s
14:00
52% 6°C 0mm 69% 0cm 59° 12°C 0mm 0.43kPa 24135m 6.3m/s 5.4m/s
15:00
75% 5.8°C 0mm 68% 0cm 54° 12°C 0mm 0.43kPa 24135m 6.2m/s 4.9m/s
16:00
98% 6.1°C 0mm 69% 0cm 47° 12°C 0mm 0.42kPa 24135m 6.6m/s 5.7m/s
17:00
95% 6.8°C 0mm 73% 0cm 38° 11°C 0.06mm 0.37kPa 24134m 7.4m/s 6.4m/s
18:00
93% 6.9°C 0mm 74% 0cm 29° 11°C 0.13mm 0.34kPa 23269m 7.8m/s 6.5m/s
19:00
90% 7.8°C 0mm 82% 0cm 20° 11°C 0.44mm 0.23kPa 14361m 9m/s 6.8m/s
20:00
60% 8°C 0mm 87% 0cm 12° 10°C 0.56mm 0.16kPa 10930m 10m/s 7.6m/s
21:00
31% 7.9°C 0mm 88% 0cm 9.9°C 1.1mm 0.15kPa 11591m 11m/s 7.3m/s
22:00
1% 7.9°C 0mm 88% 0cm -3.1° 9.8°C 1.9mm 0.14kPa 10356m 11m/s 7.9m/s
23:00
1% 8.1°C 0.01mm 88% 0cm -8.7° 10°C 2.6mm 0.15kPa 11831m 11m/s 8.6m/s
Tue, Jun 9 Sunrise 04:53 Sunset 21:38
24:00
0% 7.8°C 0mm 88% 0cm -12° 9.8°C 3.4mm 0.15kPa 7792m 11m/s 7.9m/s
01:00
0% 7.7°C 0mm 88% 0cm -14° 9.7°C 4.6mm 0.15kPa 6978m 10m/s 7.6m/s
02:00
1% 7.5°C 0mm 87% 0cm -14° 9.5°C 1.1mm 0.15kPa 9108m 10m/s 7.5m/s
03:00
2% 7.3°C 0mm 88% 0cm -11° 9.2°C 2.1mm 0.15kPa 7367m 10m/s 7.1m/s
04:00
3% 6.7°C 0mm 89% 0cm -6.2° 8.5°C 2.9mm 0.13kPa 12007m 10m/s 6.3m/s
05:00
4% 6.6°C 0mm 88% 0cm 0.5° 8.5°C 3.4mm 0.14kPa 11738m 11m/s 7m/s
06:00
4% 6.4°C 0mm 87% 0cm 7.6° 8.5°C 3.9mm 0.15kPa 15605m 10m/s 7.3m/s
07:00
5% 6.7°C 0mm 86% 0cm 16° 8.9°C 4.3mm 0.16kPa 15057m 11m/s 7.6m/s
08:00
10% 7.1°C 0mm 86% 0cm 25° 9.3°C 0.56mm 0.16kPa 9725m 11m/s 8.3m/s
09:00
16% 7.5°C 0mm 87% 0cm 34° 9.6°C 1.3mm 0.16kPa 15626m 12m/s 8.8m/s
10:00
21% 7.7°C 0mm 86% 0cm 43° 9.9°C 1.6mm 0.17kPa 17573m 11m/s 8.9m/s
11:00
18% 7.6°C 0mm 85% 0cm 51° 10°C 1.9mm 0.18kPa 20655m 11m/s 8.7m/s
12:00
16% 7.1°C 0mm 82% 0cm 57° 10°C 2.1mm 0.23kPa 23121m 11m/s 8.9m/s
13:00
13% 7.1°C 0mm 79% 0cm 60° 11°C 2.3mm 0.26kPa 19285m 12m/s 8.7m/s
14:00
31% 7.3°C 0mm 74% 0cm 59° 12°C 0.31mm 0.36kPa 12910m 11m/s 8.5m/s
15:00
48% 7.6°C 0mm 75% 0cm 54° 12°C 0.63mm 0.35kPa 17788m 11m/s 8.5m/s
16:00
66% 8.5°C 0mm 80% 0cm 47° 12°C 1.1mm 0.28kPa 16501m 11m/s 8.5m/s
17:00
62% 8.5°C 0mm 80% 0cm 38° 12°C 1.7mm 0.27kPa 13393m 10m/s 8.4m/s
18:00
57% 8.8°C 0mm 83% 0cm 29° 12°C 2.2mm 0.24kPa 15216m 9.3m/s 7.4m/s
19:00
53% 8.6°C 0mm 84% 0cm 20° 11°C 2.8mm 0.22kPa 10551m 9.4m/s 6.5m/s
20:00
41% 8.3°C 0mm 85% 0cm 12° 11°C 0.69mm 0.2kPa 9802m 9.7m/s 6.2m/s
21:00
30% 7.8°C 0mm 84% 0cm 10°C 1.4mm 0.19kPa 9557m 9.1m/s 5.4m/s
22:00
18% 7.2°C 0mm 85% 0cm -3° 9.6°C 1.9mm 0.17kPa 19354m 7.9m/s 3.9m/s
23:00
15% 7.5°C 0mm 84% 0cm -8.6° 10°C 2.2mm 0.19kPa 18112m 6.8m/s 3.7m/s
Wed, Jun 10 Sunrise 04:52 Sunset 21:38
24:00
12% 7.3°C 0.16mm 83% 0cm -12° 10°C 2.6mm 0.21kPa 16680m 6.8m/s 3.4m/s
01:00
9% 7.1°C 0.01mm 84% 0cm -14° 9.7°C 2.8mm 0.2kPa 23734m 4.2m/s 2.4m/s
02:00
8% 7°C 0mm 85% 0cm -14° 9.4°C 0.25mm 0.18kPa 24135m 6.4m/s 4m/s
03:00
7% 6.5°C 0mm 88% 0cm -11° 8.4°C 0.44mm 0.13kPa 24134m 6.6m/s 3.8m/s
04:00
6% 5.9°C 0mm 88% 0cm -6.1° 7.8°C 0.56mm 0.13kPa 22705m 7.2m/s 4.1m/s
05:00
5% 6°C 0.1mm 89% 0cm 0.54° 7.7°C 0.81mm 0.12kPa 17206m 7.9m/s 4.4m/s
06:00
4% 6.9°C 0.09mm 90% 0cm 7.6° 8.4°C 1.4mm 0.11kPa 22873m 4.7m/s 2.7m/s
07:00
3% 7.1°C 0mm 88% 0cm 16° 9°C 1.7mm 0.14kPa 13315m 7.6m/s 4.8m/s
08:00
7% 7.4°C 0mm 87% 0cm 25° 9.5°C 0.56mm 0.15kPa 12939m 8.7m/s 6.5m/s
09:00
10% 7.7°C 0mm 87% 0cm 34° 9.7°C 0.94mm 0.16kPa 15063m 8.6m/s 6.5m/s
10:00
14% 7.7°C 0mm 87% 0cm 43° 9.9°C 1.4mm 0.16kPa 12453m 8.6m/s 6.5m/s
11:00
12% 8.2°C 0mm 87% 0cm 51° 10°C 1.9mm 0.16kPa 13470m 8.6m/s 7m/s
12:00
10% 8.5°C 0mm 88% 0cm 57° 10°C 2.4mm 0.16kPa 12307m 8.7m/s 7m/s
13:00
8% 8.4°C 0mm 85% 0cm 60° 11°C 2.8mm 0.19kPa 16889m 8.6m/s 6.9m/s
14:00
19% 7.6°C 0.003mm 87% 0cm 59° 9.7°C 1.9mm 0.16kPa 19304m 6.5m/s 5.4m/s
15:00
31% 6.8°C 0.007mm 88% 0cm 54° 8.7°C 1mm 0.13kPa 21720m 4.4m/s 3.8m/s
16:00
42% 6°C 0.01mm 90% 0cm 47° 7.6°C 0.13mm 0.11kPa 24135m 2.2m/s 2.2m/s
17:00
38% 6°C 0.007mm 92% 0cm 39° 7.3°C 0.15mm 0.09kPa 24135m 2.2m/s 2.2m/s
18:00
34% 6°C 0.003mm 94% 0cm 30° 6.9°C 0.17mm 0.06kPa 24135m 2.2m/s 2.3m/s
19:00
30% 5.9°C 0mm 96% 0cm 21° 6.6°C 0.19mm 0.04kPa 24135m 2.2m/s 2.3m/s
20:00
27% 6.7°C 0mm 97% 0cm 12° 7.2°C 0.21mm 0.03kPa 17236m 4.2m/s 2.6m/s
21:00
24% 7.5°C 0mm 98% 0cm 4.1° 7.9°C 0.23mm 0.03kPa 10337m 6.1m/s 3m/s
22:00
21% 8.3°C 0mm 99% 0cm -2.9° 8.5°C 0.25mm 0.02kPa 3438m 8.1m/s 3.4m/s
23:00
16% 8.6°C 0.57mm 99% 0cm -8.5° 8.8°C 1mm 0.01kPa 2364m 8.9m/s 3.5m/s
Thu, Jun 11 Sunrise 04:52 Sunset 21:39
24:00
12% 8.9°C 1.1mm 99% 0cm -12° 9.1°C 1.8mm 0.01kPa 1290m 9.7m/s 3.6m/s
01:00
7% 9.2°C 1.7mm 99% 0cm -14° 9.4°C 2.5mm 0.01kPa 216m 11m/s 3.7m/s
02:00
6% 9.3°C 1.8mm 99% 0cm -13° 9.5°C 4.3mm 0.01kPa 278m 10m/s 3.7m/s
How to read: these inputs help produce the derived score; they are not requirements by themselves.

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