Stillwater · Ordovician Volcanics · Wales / Llŷn Peninsula (Eifionydd, Dwyfor catchment)

Llyn Cwmystradllyn

Still blue water of Llyn Cwmystradllyn with a submerged boundary fence, green hills, and an old slate quarry scar on the far hillside under a cloudy sky.
Marginal · Trout
Diawl Bach · 12-14
A patient day, if you fancy it
Good wave on — drift country. Slow going — pick your moments and do not force it.
37% confidence
limited data

Llyn Cwmystradllyn is often best in spring through autumn.

What moved it
  • WindN 21 km/hModerate breeze
Today's fly
Diawl Bach
Diawl Bach12-14
Washing-line, sub-surface
Conditions on the water
Live gauge
Wind
Moderate breeze
N 21 km/h
N
N
from the north
Wave40 cm chop
Water temp—
Air temp19°C
CloudOvercast
Pressure1019 hPa
Rain · recent0.0 mm

Some readings unavailable — check directly before fishing.

How to fish it · for Trout
When
The buzzer is on. Daddy Longlegs may also come into play as the day warms. The ripple is helpful — fish should move onto the feed and a slow-drifted team or single wet will cover water well. The breeze will be blowing terrestrial insects onto the water — check the wind lanes and downwind margins for rising fish.
Where
Set up a broadside drift and cover the water systematically. Work a bushy searching pattern on the bob and drop a contrasting nymph on the point.
The plan
Plan A

Set up a broadside drift and cover the water systematically. Work a bushy searching pattern on the bob and drop a contrasting nymph on the point.

Plan B

If the main plan is not working, switch to a smaller, more imitative pattern fished slower and deeper. A change of drift angle can also make a difference.

Watch for

Watch for Sedge towards evening — this could be the best window of the day.

Bank

Bank-only venue. Fish from accessible margins, points, weed edges, and inflows.

Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 2 guilds with Pro.

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Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 5 with Pro.

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Through the year
0–3 scale · August highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Daddy Long LegsHatch
2
3
2
Murrough (Great Red Sedge)Hatch
2
3
2
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Lake OliveHatch
1
2
2
2
2
2
1

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Trout fly box
Bays & launches · 1
Day ticket via Pwllheli & District AAAccess varies
The association's headline reservoir — stocked rainbows and blue trout over a base of wild browns, in the quieter Dwyfor catchment west of Snowdonia proper.
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What's coming
Plan ahead
5-day outlook
Condition match
59%
Cloud50%
Wind65%
Temp60%

A reasonable day here, though cloud isn't quite in the sweet spot.

Other water nearby · 5
Llyn Cwm Silyn
8.0 km
Brown trout · Arctic char
Llyn y Dywarchen
9.0 km
Brown trout · Rainbow trout
Llyn Cwm Foel
10 km
Brown trout
Llyn Llagi
10 km
Brown trout
Llyn Tecwyn Uchaf
10 km
Brown trout · Rainbow trout
Gallery · 2
  1. Still blue water of Llyn Cwmystradllyn with a submerged boundary fence, green hills, and an old slate quarry scar on the far hillside under a cloudy sky.
    Llyn Cwmystradllyn
  2. Terrain map of the venue
    Terrain map
Why this score
  • Buzzer is in its seasonal window, boosting the chance of targeted feeding.
Related guides
Stocked Trout Variantsblue, tiger & golden troutScotland Playbookloch & river fishingThermal Layers & Troutreading depth and temperature
Casting instructors near here
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