Chalk · Picardy / Somme–Pas-de-Calais border, FR

Authie

Authie terrain map

The Authie runs quietly along the old border between Picardy and the Pas-de-Calais, from Coigneux down through Auxi-le-Château and Dompierre to the Baie d'Authie where it meets the Channel in a wide tidal mouth.

Today · About as good as it gets
Czech Nymph
Forecast · Today
About as good as it gets
On the feed top to bottom — start on the rises with a dry, drop a nymph if they stay down.
90% projected
Today's fly
Czech Nymph
Czech Nymph
Conditions on the water · Today
Proxy gauge
Level
Steady
Proxy
via Scie
Water temp9.6°C
ClarityClear
Weather3°C
WindN 11 km/h
Pressure1018 hPa
Rain · recent0.4 mm
Rain · ahead14.0 mm

No gauge on this water — conditions are inferred from Scie. The trend transfers, the absolute level does not.

Water temperature for Grayling
Ideal
10°C est.ideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Autumn through November prime.
Where
Faster runs in the middle and lower stretches.
Method
Euro-nymphing through the deeper pockets is the daily default; switch to dries on autumn afternoons when sedges and small olives come off. Long fine tippet for the clear water.
Kit
10 ft #3 nymphing rod for the deep pockets; 9 ft #4 for dries. 4 to 5 lb fluoro tippet, 12 ft leader.
Why this works
Good — water temperature is working for you, but time of day is the limiting factor today. Grayling feeds actively in cold water — peak winter sport.
Likely species
Hatch timeline · todayPeak at 12pm

12pm(now) — Autumn Olive

Stage: On emergersApproach: Emerger or dryActivity: 54%
Also:Autumn Needle Fly35%Black Midge30%
Peak emergence window5 food groups active

Peak activity at 12pm — Autumn Olive (Autumn Olive, Peak emergence window)

Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 4 guilds as a supporter.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 2 as a supporter.

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Evidence
Survey-backed · regionalHigh confidence

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

Through the year
0–3 scale · November 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
2
1
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Brown SedgeHatch
2
3
3
3
2
Small SpurwingHatch
2
3
3
3
2
Small Dark OliveHatch
2
3
3
3
2

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

Ranked for today
Grayling fly box

Classic French chalkstream fishing. Gin-clear, weed-rich, slow to moderate flow. Dry fly and sight nymphing dominate. Stronger sedge hatches than English equivalents. French tradition favours flush-sitting dries (comparaduns, CDC patterns) and upstream presentation.

Small Perdigón
Small Perdigón
Hook 14–18 · Fly
in season
Permits & access
Permit required — see local rules.
  • AAPPMA and private estate water mixed
  • Estate beats around Auxi-le-Château and Nampont-Saint-Martin are well-managed
  • Some fly-only and no-kill parcours.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
About this water

It's the Canche's less-famous sister — same geology, same hatches, less pressure, and a surprising number of genuinely large fish in the lower meadows where the valley broadens. Wild brown trout through the upper reaches, grayling in the steadier pools, and a sea trout run that brings decent fish up from the bay in autumn. The mayfly comes off around the third week of May; the evening sedge hatches through June can be almost absurd. Much of the best water is private estate, but the AAPPMA beats around Auxi are good and unfussy. A river that rewards knowing it.

Hatches & food

In chalk-spring and karst trout systems, generally stable temperatures broaden olive and other mayfly activity from early spring into autumn, with strong evening caddis, steady subsurface scuds and buzzers where clear groundwater and weedbeds develop, and terrestrials from meadow and woodland banks rounding out the food calendar, depending on how fast each river drops and clears after rain.

  • Chalk
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown

WFD classification · FRAR05

The full read · show the working · for Grayling · confidence 55%
How the 76 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time15 × 13%2.0
Pressure80 × 7%5.6
Insect activity60 × 12%7.2
Conditions total= 76
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Scieproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
  • Trout 2nd Saturday of March → 3rd Sunday of September
  • Grayling 3rd Saturday of May → 31 December

    France national rule: grayling opens 3rd Saturday of May in all waters. In 2nd category waters, grayling remains open until 31 December. Departmental regulations may impose earlier closing dates. Always check the relevant département's 2026 arrêté préfectoral.

Sea trout: Variable seasonal (2026) — Authie — coastal Pas-de-Calais river between Boulogne and the Somme. Sea trout occasionally taken but not a primary sea-trout destination. Condition-sensitive; presence is localised.

Related guides
Booking & contacts
At a glance

Authie is a chalk stream in Picardy / Somme–Pas-de-Calais border, France. Its recorded elevation is about 79 m above sea level and the catchment geology is chalk. The river is described as roughly 100 km long. Our data lists brown trout, grayling and sea trout here. The trout season is recorded as running from 2nd Saturday of March to 3rd Sunday of September. The grayling season is recorded as running from 3rd Saturday of May to 31 December. Best window recorded for anglers: April–June and September. Core methods listed: Dry fly; nymphing. Its Water Framework Directive ecological status is recorded as good. Access is recorded as day tickets on a private estate. Nearby waters in our listings include Pisciculture de Monchel at 11 km, Pisciculture de Wail at 14 km and Canche at 18 km.