Spate · Mixed · South Wales / Cardiff / Caerphilly

River Rhymney

The River Rhymney flowing past Bedwas in South Wales, a gently curving rural river stretch bordered by trees.
Poor · Brown Trout
CDC Emerger · 16-18
Poorlive now
Not the day for it
River temperature is the limiting factor today, not the flow. This is not the day to push it. Check the thermal advice above before you head out.
90% confidence
What moved it
  • Level0.18 mLast reading 6h ago
  • Water temp23.0°C
  • ClarityClear
Today's fly
CDC Emerger
CDC Emerger16-18
Upstream dry, in the film
Conditions on the water
Live gauge
Level
Steady
0.18 m
Last reading 6h ago
Water temp23.0°C
ClarityClear
Weather27°C
WindW 18 km/h
Pressure1018 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

Live readings only. Trends shown where the gauge supports them.

Water temperature for Brown Trout
Warm — slow
23.0°Cideal 10–16°C
0°14°28°
How to fish it · for Brown Trout
When
Through the open trout season. Spring olives and summer sedges through the middle valley; fly life improving with catchment recovery.
Where
Middle Rhymney through the valley above the Cardiff suburbs. Pool tails and runs through farmland.
Method
Upstream dry to risers through summer; dry-dropper through the runs. Where the river slows through farmland, longer leaders and lighter tippet earn the takes. Spider patterns on the swing when olives are off the water.
Kit
9 ft #4. Floating line, 12 ft leader to 4 to 5 lb fluoro. Wading is usually easy on the lower reaches — the upper valley is rockier.
Why this works
Water at 23°C. This is the line where catch-and-release kills brown trout. Do not fish for them today.
Hatch timeline · todayPeak at 6am

Hatch predictions

Today's headline hatch shown — see all 7 active hatches hour by hour with Pro.

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Sub-surface · on the nymphunder the surface

Hatch predictions

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Beyond the hatch · worth watchingambient prey

Hatch predictions

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Evidence
Survey-backed · regionalModerate confidence

Backed by regional invertebrate surveys; no sampling on this exact reach yet.

Through the year
0–3 scale · August highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Salmon runRun
1
2
2
2
2
1
Sea trout runRun
1
2
2
2
2
2
2
1
Trout seasonSeason
1
2
2
2
2
2
1
Daddy Long LegsHatch
2
3
2
March BrownHatch
2
3
2
GrannomHatch
2
2
Large StoneflyHatch
2
3
2

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

Ranked for today
Brown Trout fly box
What's coming
Plan ahead
5-day outlook
Cooler water nearby · 1
Water here at 23.0°C — too warm to fish Brown Trout safely. These are cooler.
Bargoed Park
12 km
~23°C
Brown trout · Rainbow trout
Gallery · 2
  1. The River Rhymney flowing past Bedwas in South Wales, a gently curving rural river stretch bordered by trees.
    The River Rhymney at Bedwas, South Wales, looking west along a quiet rural stretch.
  2. Terrain map of the venue
    Terrain map
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown
What this classification means

NRW WFD Cycle 3 — Rhymney (conf Nant Cylla to Chapel Wood, Bedwas): Good ecological status. Corrected 2026-06-18 from a Nant-Glandulas tributary tag (was recorded Moderate). Source: NRW DataMapWales WFD Cycle 3 classification layer.

EA (England) · GB109057027280

The full read · show the working · for Brown Trout · confidence 90%
How the 4 is built — score × weight = contribution
Temperature2 × 28%0.6
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity54 × 12%6.5
Limiting factor: Water temperature (23°C) is outside Brown Trout's preferred range (10–16°C)= 55
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
Cooler water — back toward the 10–16 °C ideal band — would lift the score and ease welfare.
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Salmon 1 May → 17 October
  • Sea trout 3 March → 17 October
  • Trout 3 March → 30 September

Sea trout: Variable seasonal (2026) — Recovering industrial valley river; sewin work up on autumn lifts in modest numbers. All-Wales At Risk picture applies. The Rhymney's value as a fishery is in its recovery, not in destination angling.

Related guides
Yorkshire & SpidersNorth Country methodsEuro Nymphingsubsurface methods
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