Cwellyn is one of the few Welsh waters with a natural Arctic char population — eighty-seven hectares of deep glacial lake (max 37 m) on the Afon Gwyrfai, at the foot of Snowdon. SAC-designated. Wild brown trout shoreward; char in the deep water (you'll need a boat to fish them properly), and the occasional salmon working up the Gwyrfai. The setting is what it is — Snowdon's western flank behind you, Moel Eilio in front.
A patient day, if you fancy it
Glassy and bright — hard work without a breeze. A flat lough is a quiet lough — wait for the breeze.
34% confidence — limited data
Live now
Conditions on the water
Trends shown where the gauge supports them
Wind
SW 38 km/h
Fresh breeze
Wave
80 cm wave
Water temp
—
No reading
Air temp
11°C
Cloud
Broken
Pressure
990 hPa
Rain · 24h
0.0 mm
No rain
Some readings unavailable — check directly before fishing.
How to fish · for brown trout
The brief
When · where · method · kit
How to fish it · for brown trout
When
The buzzer is on. Sedge may also come into play as the day warms. Strong wind will make open-water drifting difficult. Look for sheltered bays and lee shores.
Where
With limited drift, anchor or fish static from sheltered positions. Work Dry Fly on the bob and Terrestrial on the point. Drop the droppers and fish a single fly in this wind — tangles cost more time than a second pattern catches.
Today's tactical plan
The plan
Plan A · Plan B · what to watch · bank or boat
The plan
Plan A
With limited drift, anchor or fish static from sheltered positions. Work Dry Fly on the bob and Terrestrial on the point. Drop the droppers and fish a single fly in this wind — tangles cost more time than a second pattern catches.
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
Evening tends to be the best period in summer — stay late if you can for a sedge or spinner fall.
Bank, sheltered shores
Strong wind makes boat fishing difficult — sheltered bank spots near lee shores will fish best.
Hatches & runs
What's on, when
Twelve months at a glance
Through the year
0–3 scale · June highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Daddy Long LegsHatch
2
3
2
Murrough (Great Red Sedge)Hatch
1
2
1
Lake OliveHatch
1
2
2
2
2
2
1
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Today's fly · curated pack
Top pattern + the box
6 patterns from this venue's curated pack
Evidence
Why today scores what it does
The factors driving today's verdict
Why this score
- Wind conditions (strong) are not ideal for this water.
- Buzzer is in its seasonal window, boosting the chance of targeted feeding.
Access · 1
Check the current rules, permits and access before travelling.
Day ticket via Fishing PassportSeiont, Gwyrfai a Llyfni (SGLL) Fishing Society (via Fishing Passport)
Wild brown troutArctic char / torgochFlySpinBait
87-hectare SAC-designated glacial lake at the foot of Snowdon — wild brown trout, natural Arctic char (torgoch) population, occasional salmon. Char need a boat. SGLL ticket.
Day £25, weekly £90 — SGLL ticket. Boat needed for char. EA/NRW rod licence required (migratory endorsement for salmon). SAC water — care with disturbance.
Arrange access →About this water · Lough note · 4 min read
Llyn Cwellyn · profile
Who this water suits
Strengths · watch-outs · best for
About this water
Llyn Cwellyn, on the water
Field guide · contributor-editedLlyn Cwellyn · about
What this water is
Background · character · contributors
About this water
Cwellyn is one of the few Welsh waters with a natural Arctic char population — eighty-seven hectares of deep glacial lake (max 37 m) on the Afon Gwyrfai, at the foot of Snowdon. SAC-designated. Wild brown trout shoreward; char in the deep water (you'll need a boat to fish them properly), and the occasional salmon working up the Gwyrfai. The setting is what it is — Snowdon's western flank behind you, Moel Eilio in front.
- Lake
- Ordovician volcanics
Llyn Cwellyn · directions
How to get to the water
Directions
Llyn Cwellyn
Cwellyn is one of the few Welsh waters with a natural Arctic char population — eighty-seven hectares of deep glacial lake (max 37 m) on the Afon Gwyrfai, at the foot of Snowdon.
Species
A patient day, if you fancy it
Glassy and bright — hard work without a breeze. A flat lough is a quiet lough — wait for the breeze.
34% confidence — limited data
Conditions
Wind
SW 38 km/h
Fresh breeze
Wave
80 cm wave
Water temp
—
No reading
Air temp
11°C
Cloud
Broken
Pressure
990 hPa
Rain · 24h
0.0 mm
No rain
Some readings unavailable — check directly before fishing.
Condition match
41%
Cloud70%
Wind30%
Temp25%
Conditions are away from this venue's sweet spot — it usually fishes best in ripple wind with mixed skies.
How to fish it · for brown trout
When
The buzzer is on. Sedge may also come into play as the day warms. Strong wind will make open-water drifting difficult. Look for sheltered bays and lee shores.
Where
With limited drift, anchor or fish static from sheltered positions. Work Dry Fly on the bob and Terrestrial on the point. Drop the droppers and fish a single fly in this wind — tangles cost more time than a second pattern catches.
The plan
Plan A
With limited drift, anchor or fish static from sheltered positions. Work Dry Fly on the bob and Terrestrial on the point. Drop the droppers and fish a single fly in this wind — tangles cost more time than a second pattern catches.
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
Evening tends to be the best period in summer — stay late if you can for a sedge or spinner fall.
Bank, sheltered shores
Strong wind makes boat fishing difficult — sheltered bank spots near lee shores will fish best.
Why this score
- Wind conditions (strong) are not ideal for this water.
- Buzzer is in its seasonal window, boosting the chance of targeted feeding.
Through the year
0–3 scale · June highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Daddy Long LegsHatch
2
3
2
Murrough (Great Red Sedge)Hatch
1
2
1
Lake OliveHatch
1
2
2
2
2
2
1
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Access · 1
Check the current rules, permits and access before travelling.
Day ticket via Fishing PassportSeiont, Gwyrfai a Llyfni (SGLL) Fishing Society (via Fishing Passport)
Wild brown troutArctic char / torgochFlySpinBait
87-hectare SAC-designated glacial lake at the foot of Snowdon — wild brown trout, natural Arctic char (torgoch) population, occasional salmon. Char need a boat. SGLL ticket.
Day £25, weekly £90 — SGLL ticket. Boat needed for char. EA/NRW rod licence required (migratory endorsement for salmon). SAC water — care with disturbance.
Arrange access →Directions
About this water
Cwellyn is one of the few Welsh waters with a natural Arctic char population — eighty-seven hectares of deep glacial lake (max 37 m) on the Afon Gwyrfai, at the foot of Snowdon. SAC-designated. Wild brown trout shoreward; char in the deep water (you'll need a boat to fish them properly), and the occasional salmon working up the Gwyrfai. The setting is what it is — Snowdon's western flank behind you, Moel Eilio in front.
- Lake
- Ordovician volcanics
About this water · Lough note · 4 min read
Cwellyn is one of the few Welsh waters with a natural Arctic char population — eighty-seven hectares of deep glacial lake (max 37 m) on the Afon Gwyrfai, at the foot of Snowdon. SAC-designated. Wild brown trout shoreward; char in the deep water (you'll need a boat to fish them properly), and the occasional salmon working up the Gwyrfai. The setting is what it is — Snowdon's western flank behind you, Moel Eilio in front.
Other water nearby · 5