Freestone · Limestone · Primorska

Idrijca

The Idrijca river near Most na Soči, Slovenia, with clear green water.
Fair · Grayling
F-fly · sizes_14_18
Temporary closure · troutReported 31 Jul 2026

Total fishing suspension in force (low water / high temperature)

RD Idrija had a total suspension of fishing in force as of 31 July 2026 for low water and high water temperature, alongside a national low-water welfare warning live on ribiskekarte.si. This is a biophysical do-not-fish state, not a routine seasonal closure — check RD Idrija's current notice before travelling.

RD Idrija club announcements ↗

Temporary notices from official orders and recent fishery reports — they clear automatically once out of date. Always confirm locally before travelling.

Fairlive now
A side-water session, not the main event
River lifting fast on the rain. Take your time — read the water before you cast.
65% confidence
What moved it
  • Level71.00 mLifting fast
  • Water temp11.2°C
  • ClarityVery colouredColouring up
Today's fly
F-fly
F-flysizes_14_18
in season · matches water height
Conditions on the water
Live gauge
Level
Rising
71.00 m
Lifting fast
Water temp11.2°C
ClarityVery coloured
Weather24°C
WindE 17 km/h
Pressure1023 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

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

Water temperature for Grayling
Ideal
11.2°Cideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Autumn through November is prime — September into November the grayling get serious. Cold water, midday warmth, and the duns and spinners that come off the limestone runs.
Where
Faster water at the heads of pools and through the riffles — gravel runs where grayling shoal up. Deeper glide tails into autumn as the water cools.
Method
Euro-nymphing primary — Perdigons and dropper-rigged spider patterns through the pocket water. Switch to dries when sedges or olives come off. Slovenian grayling are particular about presentation.
Kit
10 ft #3 nymphing rod is the default; 9 ft #4 if you'd rather dry-fish. 4 to 5 lb fluoro tippet, 12 ft leader.
Why this works
Good — water temperature is working for you, but insect activity is the limiting factor today.
Likely species
Mayflies
  • Blue-winged oliveMost likely
    #16–18 · Dun
    Duns are up; a sherry spinner fall may follow.
  • Anglers curse mayfliesAlso possibleLower confidence
    #20–22 · Spinner
    Go tiny: 20-22 spent spinner, single fly, long tippet.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 2 active hatches hour by hour with Pro.

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Sub-surface · on the nymphunder the surface

Hatch predictions

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Evidence
ModelledModerate confidence

Modelled from regional ecology — no survey or occurrence data for this water yet.

Updated 23 hours ago

Through the year
0–3 scale · August highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Grayling seasonSeason
1
2
2
2
2
2
1
GrannomHatch
2
2
Evening SedgeHatch
2
3
3
3
2
Alpine RhithrogenaHatch
1
2
2
1
Large Dark OliveHatch
1
2
2
1

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

Ranked for today
Grayling fly box
PT
Pink Tag Jig Nymph
sizes_14_18 · Fly
off-peak month · matches water height
Permits & access
Permit required — see local rules.
  • Fishing licence + permit from ribiške družine
  • No live bait.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Cerknica (Idrijca tributary)
8.0 km
64
Marble trout · Marble brown hybrid trout · Brown trout
Kanomljica
6.0 km
Marble trout · Marble brown hybrid trout · Brown trout
Hubelj
13 km
Marble trout · Marble brown hybrid trout · Brown trout
Kneža
16 km
Marble trout · Brown trout · Grayling
Vipava
17 km
Marble trout · Marble brown hybrid trout · Brown trout
Gallery · 6
  1. The Idrijca river near Most na Soči, Slovenia, with clear green water.
    Idrijca near Most na Soči
  2. The Idrijca flowing through the rocky Strug gorge between Podroteja and Idrijska Bela.
    Idrijca in the Strug gorge
  3. Wide landscape view of the Idrijca upstream from Idrijska Bela, Slovenia.
    Idrijca upstream from Idrijska Bela
  4. The Idrijca running through the Strug gorge with steep rocky banks.
    Idrijca in the Strug gorge
  5. The Idrijca at Spodnja Idrija, Slovenia, the river channel through the valley.
    Idrijca at Spodnja Idrija
  6. Terrain map of the venue
    Terrain map
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown

WFD classification · SI62VT13

The full read · show the working · for Grayling · confidence 65%
How the 64 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow30 × 22%6.6
Clarity45 × 18%8.1
Feeding Time95 × 13%12.4
Pressure80 × 7%5.6
Insect activity26 × 12%3.1
Conditions total= 64
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
A drop and clear would lift the flow and clarity scores.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout 1 March → 30 September
  • Grayling 16 May → 30 November

    Slovenian common default: grayling 16 May – 30 November (lipan). Slovenia is permit and fishing district controlled — dates may vary by specific water. Always check the Ribiška Družina (fishing district) permit for the specific beat. The Soča, Idrijca, and Sava system hold world-class grayling alongside marble trout.

    Prime sport 1 September → 30 November

  • Marble trout 1 April → 31 October
Related guides
Grayling Playbookgrayling tacticsAlpine Streamsmountain entomologyMarble TroutSoča system
Booking & contacts