Llyn Cefni is Anglesey's second principal stillwater — a modest reservoir managed for public fly fishing. It produces solid sport on buzzers and nymphs, with bank access and occasional boat availability. The shallow limestone water means reliable food chains and consistent hatches. Spring and early summer are best; autumn can be productive after a spate. This is a straightforward day-ticket water — no pretense, no drama, just a chance to be on trout in a genuine wild setting. The Anglesey isolation gives even this workhorse water a quiet, undisturbed feel.
Good late spring conditions for Llyn Cefni Reservoir
Useful ripple, fishable wave. Worth a session if the wind holds.
Conditions are not ideal but fishable at Llyn Cefni Reservoir.
62% confidence in this read
Live now
Conditions on the water
Trends shown where the gauge supports them
Wind
W 27 km/h
Moderate breeze
Wave
60 cm wave
Water temp
—
No reading
Air temp
9°C
Cloud
Overcast
Pressure
—
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
Conditions are not ideal but fishable at Llyn Cefni Reservoir.
Where
Start with Diawl Bach (12-14) — on the bob / top dropper — slow figure-of-eight retrieve. If that does not produce, switch depth or speed before changing the pattern entirely.
Method
Method not yet authored.
Kit
Kit not yet authored.
Today's tactical plan
The plan
Plan A · Plan B · what to watch · bank or boat
The plan
Plan A
Start with Diawl Bach (12-14) — on the bob / top dropper — slow figure-of-eight retrieve. If that does not produce, switch depth or speed before changing the pattern entirely.
Plan B
If fish refuse on top, drop to a buzzer under an indicator at different depths.
Watch for
Keep an eye on changing conditions — wind shifts and cloud breaks can trigger short feeding spells.
Bank, sheltered shores
In wind, bank fish the lee shore — boats can anchor in productive areas if conditions allow.
Hatches & runs
What's on, when
Twelve months at a glance
Through the year
0–3 scale · May highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
2
1
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Reservoir BuzzerHatch
2
3
3
3
3
3
2
Daphnia SwarmHatch
2
3
3
3
2
Lake OliveHatch
2
3
3
3
3
3
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Today's fly · curated pack
Top pattern + the box
3 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 (windy) are not ideal for this water.
- Temperature (cool) is in the sweet spot for late spring fishing.
- Hawthorn Fly is in its seasonal window, boosting the chance of targeted feeding.
Detail · next 12h
Precipitation
The reading most likely to move tomorrow's verdict
About this water · Lough note · 4 min read
About this water
Llyn Cefni Reservoir, on the water
Field guide · contributor-editedLlyn Cefni Reservoir · about
What this water is
Background · character · contributors
About this water
Llyn Cefni is Anglesey's second principal stillwater — a modest reservoir managed for public fly fishing. It produces solid sport on buzzers and nymphs, with bank access and occasional boat availability. The shallow limestone water means reliable food chains and consistent hatches. Spring and early summer are best; autumn can be productive after a spate. This is a straightforward day-ticket water — no pretense, no drama, just a chance to be on trout in a genuine wild setting. The Anglesey isolation gives even this workhorse water a quiet, undisturbed feel.
- Reservoir
- Limestone
Llyn Cefni Reservoir · directions
How to get to the water
Directions
Llyn Cefni Reservoir · zones
Where the rules change
Seasons · zones · per-species rules
Seasons & zones
- Trout15 March → 5 October
Llyn Cefni Reservoir
Terrain map
Llyn Cefni is Anglesey's second principal stillwater — a modest reservoir managed for public fly fishing.
Species
Good late spring conditions for Llyn Cefni Reservoir
Useful ripple, fishable wave. Worth a session if the wind holds.
Conditions are not ideal but fishable at Llyn Cefni Reservoir.
62% confidence in this read
Conditions
Wind
W 27 km/h
Moderate breeze
Wave
60 cm wave
Water temp
—
No reading
Air temp
9°C
Cloud
Overcast
Pressure
—
Rain · 24h
0.0 mm
No rain
Some readings unavailable — check directly before fishing.
Condition match
57%
Cloud50%
Wind30%
Temp100%
A reasonable day here, though wind isn't quite in the sweet spot.
How to fish it · for brown trout
When
Conditions are not ideal but fishable at Llyn Cefni Reservoir.
Where
Start with Diawl Bach (12-14) — on the bob / top dropper — slow figure-of-eight retrieve. If that does not produce, switch depth or speed before changing the pattern entirely.
Method
Method not yet authored.
Kit
Kit not yet authored.
The plan
Plan A
Start with Diawl Bach (12-14) — on the bob / top dropper — slow figure-of-eight retrieve. If that does not produce, switch depth or speed before changing the pattern entirely.
Plan B
If fish refuse on top, drop to a buzzer under an indicator at different depths.
Watch for
Keep an eye on changing conditions — wind shifts and cloud breaks can trigger short feeding spells.
Bank, sheltered shores
In wind, bank fish the lee shore — boats can anchor in productive areas if conditions allow.
Why this score
- Wind conditions (windy) are not ideal for this water.
- Temperature (cool) is in the sweet spot for late spring fishing.
- Hawthorn Fly is in its seasonal window, boosting the chance of targeted feeding.
Through the year
0–3 scale · May highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
2
1
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Reservoir BuzzerHatch
2
3
3
3
3
3
2
Daphnia SwarmHatch
2
3
3
3
2
Lake OliveHatch
2
3
3
3
3
3
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Directions
About this water
Llyn Cefni is Anglesey's second principal stillwater — a modest reservoir managed for public fly fishing. It produces solid sport on buzzers and nymphs, with bank access and occasional boat availability. The shallow limestone water means reliable food chains and consistent hatches. Spring and early summer are best; autumn can be productive after a spate. This is a straightforward day-ticket water — no pretense, no drama, just a chance to be on trout in a genuine wild setting. The Anglesey isolation gives even this workhorse water a quiet, undisturbed feel.
- Reservoir
- Limestone
Seasons & zones
- Trout15 March → 5 October
About this water · Lough note · 4 min read
Llyn Cefni is Anglesey's second principal stillwater — a modest reservoir managed for public fly fishing. It produces solid sport on buzzers and nymphs, with bank access and occasional boat availability. The shallow limestone water means reliable food chains and consistent hatches. Spring and early summer are best; autumn can be productive after a spate. This is a straightforward day-ticket water — no pretense, no drama, just a chance to be on trout in a genuine wild setting. The Anglesey isolation gives even this workhorse water a quiet, undisturbed feel.
Other water nearby · 5