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.
Fair · Trout
Minkie · 6-10
A respectable few hours, if you choose your moments
Good wave on — drift country. A useful wave. Work the productive shore.
45% confidence
limited data

Llyn Cwmystradllyn is often best in spring through autumn.

What moved it
  • WindN 9 km/hLight breeze
Today's fly
Minkie
Minkie6-10
Retrieve, sub-surface
Conditions on the water
Estimate
Wind
Light breeze
N 9 km/h
N
N
from the north
WaveRipple
Water temp—
Air temp11°C
CloudBroken
Pressure1023 hPa
Rain · recent0.0 mm

No gauge on this water — readings are regional estimates from weather, not a live gauge.

How to fish it · for Trout
When
The sedge 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.
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. Keep a sedge-style dry or emerger on a short leader for the evening rise.
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. Keep a sedge-style dry or emerger on a short leader for the evening rise.

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

Sedge should come on through the afternoon as the water warms.

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 3 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
Heather FlyHatch
2
2
Daddy Long LegsHatch
2
3
2
Claret DunHatch
2
3
2
Murrough (Great Red Sedge)Hatch
2
3
2

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
88%
Cloud100%
Wind100%
Temp60%

Conditions are ideal for Llyn Cwmystradllyn — wind, cloud and temperature all line up.

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
  • Wind conditions (ripple) closely match what this water fishes best in.
  • Cloud cover (cloud) suits the fishery well.
  • Sedge 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
Booking & contacts