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Where to fish

  • Forecast
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Forecast
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© 2026·AI-powered bite forecast
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United Kingdom / Powys / River Irfon

Bite forecast: River Irfon

  • length 47 km
Loading map…

Best fishing days for the next week

  1. TuesdaySeptember 8weather-based forecast
    64/100high activity

    Cloudy: 10–17 °C

  2. SundaySeptember 6weather-based forecast
    62/100high activity

    Cloudy: 15–19 °C

  3. ThursdaySeptember 3weather-based forecast
    59/100medium activity

    Cloudy: 15–19 °C

Nearby towns

  • Llanwrtyd Wells0 mi
  • Builth Wells0.4 mi
  • Llandrindod Wells6 mi

River Irfon (Powys) — one of the area's fishing spots. About 47 km long. Close by — Llanwrtyd Wells, Builth Wells and Llandrindod Wells. A smart bite calendar — moon phase, atmospheric pressure, and weather combined into an hourly fish-activity forecast for the coming days.

BiteGuide·From anglers’ reports

What actually worked on this water

Based on 7 verified catchesPeriod: 2015–2022

This is a summary of anglers' reports, not a proven cause of the bite: conditions lining up does not mean they drove it.

By fish species

vertical axis — number of catches

035
511
GraylingAtlantic salmonBrown trout
By fish species
ValueCatchesShare
Grayling571%
Atlantic salmon114%
Brown trout114%

By month

vertical axis — number of catches

023
2113
JanFebMayOct
By month
ValueCatchesShare
Jan229%
Feb114%
May114%
Oct343%

By time of day

vertical axis — number of catches

023
11131
911121317
By time of day
ValueCatchesShare
09:00114%
11:00114%
12:00114%
13:00343%
17:00114%

Air temperature, °C

vertical axis — number of catches

023
331
01015
Air temperature, °C
ValueCatchesShare
0–4 °C343%
10–14 °C343%
15–19 °C114%

Pressure, mmHg

vertical axis — number of catches

024
142
745750765
Pressure, mmHg
ValueCatchesShare
745–749 mmHg114%
750–754 mmHg457%
765–769 mmHg229%

Wind direction

vertical axis — number of catches

023
1213
NEESWW
Wind direction
ValueCatchesShare
NE114%
E229%
SW114%
W343%

Wind speed, mph

vertical axis — number of catches

023
223
049
Wind speed, mph
ValueCatchesShare
0–2 mph229%
4–7 mph229%
9–11 mph343%
Loading map…

Catches

Recorded 7 catches here. Most commonly caught: Grayling, Brown trout, Atlantic salmon. Peak season: year-round.

  • Brown trout
    River Irfon
    15 °C11 mph
    May 21, 2022, 8:45 AM
  • Grayling
    River Irfon

Bite calendar

7–Sep 13
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Bite activity:highmediumlowslow
Based on:weatherseasonal
What is a bite calendar?

In the fish list, this icon marks species recorded here by GBIF. Unmarked species may still occur in the waterbody.

European eelPikeWhitefishBarbelWels catfishDaceGraylingRuffeZanderAtlantic salmonBreamBrown troutCarpPerchRainbow troutChubIdeCrucian carpRoachWhite breamBleakRuddTench

Atlantic salmon

7/10 · Good

Occurs in this waterbody — confirmed by observations. Source: GBIF

Hourly activity

0:006:0012:0018:0023:00
Bite activity:highmediumlow

The bite is strong — fish are active. Pressure is dropping — this usually boosts the bite.

Peak bite hours

Best time — 06:00–08:00 (dawn bite) and 19:00–21:00 (dusk bite).

Tactics

Work the cover — snags, weed edges, hole entrances; retrieve the lure with pauses.

Lures

The water's turning murky — go with bright, noisy lures: salmon spoon or salmon fly.

Gear

Pack transitional-season clothing — mornings and evenings are chilly. Rain is expected — don't forget a rain jacket or a waterproof shell.

Summary

Worth going — it's a productive day.

How this forecast is calculated

Why this forecast

The computed water temperature is around 14 °C — inside the 4–14 °C comfort range for Atlantic salmon, so baseline activity is high.

Computed water temperature by month; the green band is the 4–14 °C comfort rangecomfort 4–14 °C14 °C
JFMAMJJASOND

Atlantic salmon works the twilight: the peaks are pinned to sunrise and sunset — their times are in the sun-and-moon card above.

The day: daylight hours and when Atlantic salmon feeds0:0012:0024:00

Pressure is dropping 33 hPa over the day — fish are usually more active ahead of a weather change.

Pressure through the day, 33 hPa change
00:00 · 101923:00 · 986 hPa

One more input — the moon's feeding windows: within their hours the score sits higher than across the rest of the day. The window times are in the “Solunar feeding periods” card below.

Feeding windows on the day scale0:0012:0024:00

September is an active season for Atlantic salmon here.

JFMAMJJASOND

These are the same values the bite curve above was computed from. How the forecast works

8 SepTuesday, September 8
+14°

Cloudy · feels like +10°

Low / high
+10°…+17°
Precipitation
0.5 mm
Wind
15 mph SW
Cloud cover
100%
Humidity
79%
Pressure
1013 hPa
00:00+12°0.4 mm12 mphwest wind, 12 mph93%100%
01:00+12°0.4 mm11 mphwest wind, 11 mph93%100%
02:00+12°—11 mphwest wind, 11 mph93%100%
03:00+11°—10 mphwest wind, 10 mph93%100%
04:00+11°—10 mphwest wind, 10 mph92%100%
05:00+10°—9 mphwest wind, 9 mph92%100%
06:00+10°—9 mphwest wind, 9 mph90%100%
07:00+10°—9 mphwest wind, 9 mph88%100%
08:00+11°—9 mphwest wind, 9 mph85%100%
09:00+11°—9 mphwest wind, 9 mph80%100%
10:00+12°—9 mphwest wind, 9 mph75%100%
11:00+13°0.2 mm12 mphwest wind, 12 mph76%100%
12:00+14°0.5 mm15 mphsouthwest wind, 15 mph79%100%
13:00+14°0.7 mm19 mphsouthwest wind, 19 mph85%100%
14:00+15°1.6 mm21 mphsouth wind, 21 mph93%100%
15:00+15°1.6 mm21 mphsouth wind, 21 mph94%100%
16:00+16°1.6 mm20 mphsouthwest wind, 20 mph95%100%
17:00+16°1.6 mm19 mphsouthwest wind, 19 mph96%100%
18:00+16°1.6 mm18 mphsouthwest wind, 18 mph97%99%
19:00+17°1.6 mm17 mphsouthwest wind, 17 mph98%99%
20:00+16°0.2 mm18 mphsouthwest wind, 18 mph98%98%
21:00+16°0.2 mm19 mphsouthwest wind, 19 mph98%98%
22:00+15°0.2 mm21 mphsouthwest wind, 21 mph98%97%
23:00+14°0.2 mm22 mphsouthwest wind, 22 mph97%96%
+17°+13°+10°
Weather throughout the day
0:006:0012:0018:0023:00

Sun and moon

Tuesday, September 8
The day: daylight and the hours the moon is above the horizon. Local time0:0012:0024:00
DaylightMoon above the horizon
Sunrise
06:36
Sunset
19:45
Day length
13 h 9 min
Sunshine hours
0 min
UV index
1
low
Moon
Waning crescent
Moonrise
02:43
Moonset
18:50

The day is 4 min shorter than yesterday.

Sunshine hours count direct sun only — cloud cover cuts it, so it is shorter than daylight.

Solunar feeding periods

+11% in the windowTuesday, September 8
Feeding windows on the day scale, local time0:0012:0024:00
Major periodsMinor periods
  • Minor02:13–03:13Moonrise
  • Major09:58–11:58Moon overhead
  • Minor18:20–19:20Moonset
  • Major22:25–00:00Moon underfoot

The windows are set by the moon's transit and rise, and the forecast above already accounts for them: within these hours the bite score sits higher than across the rest of the day, while the day's overall level still comes from the catch-calibrated model.

What are solunar periods?
0 °C2 mph
Jan 03, 2019, 1:27 PM
  • Grayling
    River Irfon
    0 °C2 mph
    Jan 03, 2019, 12:28 PM
  • Atlantic salmon
    River Irfon
    13 °C11 mph
    Oct 07, 2017, 12:58 PM
  • Grayling
    River Irfon
    11 °C7 mph
    Oct 20, 2016, 12:28 PM
  • Grayling
    River Irfon
    4 °C9 mph
    Feb 18, 2016, 5:00 PM
  • Grayling
    River Irfon
    14 °C7 mph
    Oct 08, 2015, 10:17 AM
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