Six months on the water. Pick the right one.
The fly fishing season in Chilean Patagonia runs from November 1 to April 30 each year. Below is a month-by-month breakdown of water conditions, fly patterns that produce, weather, wind and the species in play. Twelve years of field notes from Puerto Natales, distilled.
The Chilean Patagonia fly fishing season is set by Sernapesca regulation and runs November 1 through April 30 across the Magallanes region. The two best months by every measurable metric — stable weather, low wind, clear water, hatch density, willing fish — are February and March. November opens with high water and big streamers; April closes with the largest fish of the year and the coldest mornings. The season's first sea-run brown trout typically enter the Río Serrano during the last week of February.
The six months at a glance.
Tap a month to jump to the full conditions report.
November · Opening.
November is the high-water month. Snowmelt from the southern Patagonian icefield is at its peak and the Río Serrano typically runs 30–40% above its summer baseline. The season opens on November 1 with cold mornings, fresh rainbows that haven't seen a fly in five months, and the most reliable streamer fishing of the year.
Water level & clarity
High and pushy. Río Serrano carries glacial milk well into the month; clarity is 60–90 cm on the main stem. Smaller spring creeks like Las Chinas are already clearing — that's where the dry-fly hunter goes early.
Weather
- Typical high: 14°C / 57°F · typical low: 3°C / 37°F.
- Frost mornings are common in the first two weeks.
- Day length is excellent: 16+ hours of usable light by mid-month.
Wind
Heavy. November is one of the windiest months — typical afternoon gusts run 40–60 km/h, with peak gusts to 80 km/h. We plan beats east-to-west whenever possible and fish sheltered bank lies through the afternoon. Mornings are reliably calm.
Hatches & insect activity
Light. The big mayfly and caddis hatches that anchor the summer fishing do not yet build. The exception is a small black midge cluster that the fish key on at midday in the lakes. Worm-pattern nymphs (San Juan Worm, Squirmy Wormy) move fish in stained water.
Best rod weights & lines
- 5-weight floating — for the cleared spring creeks.
- 6-weight with a 10-ft sink tip — for the Serrano main stem.
- 7-weight with full sinking line — for big streamers on heavy water.
Best species & flies
- Rainbow trout on streamers: Galloup's Peanut Envy, Sex Dungeon size 4 (black/yellow), Conehead Bunny Leech size 4.
- Brown trout waking up in the spring creeks: small black Wooly Buggers and the first Parachute Adams of the season.
- Don't bother with salmon or sea-run brown trout — they're still in the sound.
Notable events
November 1 opener · 16+ hour days · snowmelt peak around the 20th. First fish of the season is usually a 3–4 lb rainbow on a black streamer in the lowest pool of the Serrano. We've kept records every year since 2014.
December · Building.
December is when summer fishing arrives. Water levels drop steadily through the month, the spring creeks come fully into their own, the first reliable dry-fly action of the season opens up, and the king salmon begin to push into the estuary. Wind is still serious but the days get long and warm.
Water level & clarity
Dropping. Río Serrano clears by mid-December to 1.2–1.8 m visibility. Spring creeks are at summer pool — gin clear, slow, and demanding. By the last week of December the river is in "summer mode."
Weather
- Typical high: 17°C / 63°F · typical low: 6°C / 43°F.
- The longest days of the year — 17 hours of usable light around the solstice.
- Rain events shorter, sun stronger. UV index hits 10+ — bring sunblock.
Wind
Still significant. December is the second-windiest month after November. Afternoon gusts 30–50 km/h. Mornings before 11 AM are reliably the calm window.
Hatches & insect activity
Ramps up sharply through the month. Caddis (tan and olive, size 14–16) come off the spring creeks in the afternoon. Terrestrials (hoppers, ants, beetles) begin to factor in the last two weeks. PMD-style mayfly hatches build on the slow runs.
Best rod weights & lines
- 5-weight — primary trout rod, floating line, leaders to 12 ft.
- 6-weight — for hopper-dropper and big bank streamers.
- 8-weight Skagit — for the first king salmon work in the estuary.
Best species & flies
- Rainbow trout on hopper-dropper: Morrish Hopper size 10 over Pheasant Tail nymph size 16.
- Brown trout first sight-fish opportunities on the spring creeks: Parachute Adams 16, CDC Caddis 14 tan.
- King salmon staging in the estuary in the last 10 days: Comet pattern, size 1/0 pink/orange.
Notable events
December 21 solstice · longest day of the year (17h 12m of daylight at Puerto Natales). First king salmon usually in the estuary the week before Christmas. Last week of December is the inflection point of the season — water clears, hatches build, and the fishing becomes pattern-driven.
January · Peak summer.
January is the most complete fishing month of the season. Water is at summer pool, hatches are at full strength, rainbows eat dries, the biggest resident brown trout come into play in the spring creeks, and king salmon stage in the deep pools of the Serrano. The day-to-day variety is unmatched.
Water level & clarity
Summer pool. Río Serrano runs at base flow with 1.8–2.5 m visibility. Spring creeks are gin clear and fish are spooky from the second week onwards. Lago Sarmiento is calm and sight-fishable from a skiff.
Weather
- Typical high: 19°C / 66°F · typical low: 8°C / 46°F.
- The warmest sunny days of the year. Strip a layer at midday.
- Rain events brief but possible. Pack a packable shell.
Wind
Easier than December. Afternoon gusts average 25–40 km/h. The evening calms reliably from about 8 PM. Plan technical dry-fly work for the first hour after sunrise and the last two hours before sunset.
Hatches & insect activity
Peak. Terrestrials (hoppers, beetles, ants) dominate the bank. Caddis come off morning and evening. PMD-style mayflies in the spring creeks. The full hopper-dropper season is open.
Best rod weights & lines
- 5-weight — every spring creek day. Tapered leaders to 14 ft, 5X fluorocarbon.
- 6-weight — bank streamer hunting and hopper days.
- 8-weight Skagit — king salmon work, T-14 sink tip.
Best species & flies
- Rainbow trout: Chubby Chernobyl size 8 over a tungsten Hare's Ear size 14. The single most productive setup of the month.
- Brown trout: Parachute Adams 16, foam beetle 14, Morrish Hopper 10 against the cut banks.
- King salmon: Comet 1/0, pink/purple Intruder, dead-drift through the staging pools of the lower Serrano.
Notable events
January 15 — peak king salmon stage · the busiest fishing month for booked weeks, every year. 80% of January Saturdays sell out by October. Largest king to date in January is a 24-pound buck taken on the Serrano in January 2024.
February · The dry-fly month.
February is the best month of the season for dry-fly fishing. The most stable weather of the year, the lowest average winds, the highest sustained water temperatures, and the most willing surface fish. The first sea-run brown trout enter the river in the last week. If you can only book one week, book the last week of February.
Water level & clarity
At summer base. Río Serrano carries 2.0–3.0 m visibility in the main stem. Spring creeks at their clearest of the season — 5X tippet is the minimum, 6X helps on the slowest pools.
Weather
- Typical high: 18°C / 64°F · typical low: 7°C / 45°F.
- The most stable month of the season. Storms shorter, fronts weaker.
- Day length still excellent: 15 hours at the start, 14 by month-end.
Wind
The lightest of the season. Average afternoon gusts 15–25 km/h. We routinely fish 5-weights with technical dry-fly presentations through the whole afternoon — something not possible in November or December.
Hatches & insect activity
Sustained peak. Hoppers on the bank, caddis morning and evening, spinner falls on the slow pools at sunset, beetles on the wind. The fish look up all day. This is the surface-eaters' month.
Best rod weights & lines
- 4-weight — for the most technical spring-creek work, an option in February only.
- 5-weight — primary rod, 95% of fishing.
- 7-weight Skagit — for the first sea-run work in the last week.
Best species & flies
- Brown trout: sight-fished dries on the spring creeks — Parachute Adams 16, CDC Caddis 14, foam beetle 14. The single most productive month for big browns on dries.
- Rainbow trout: Chubby Chernobyl 8, foam hoppers, evening caddis.
- Sea-run brown trout: arriving in the last week. Conehead Bunny Leech size 4 on a sink tip.
Notable events
February 22–28: first sea-run brown trout · the inflection week. Our records show first sea-run landed on Feb 24 (2023), Feb 26 (2024), Feb 23 (2025). Booking demand is highest for this window — Feb 20 through March 15 sells out 9+ months in advance.
March · The trophy month.
March is the peak of the sea-run brown trout migration. Trout fishing on the spring creeks remains excellent through the first half of the month. Then attention shifts. Chrome fish in the 8–18 pound class push into the Río Serrano. Our largest sea-runs of every season are caught in March.
Water level & clarity
Low and clear. Río Serrano at its lowest of the year. Spring creeks still gin clear but trout become wary as light angles change. The estuary draws more attention — saltwater fishing from the skiff for fresh sea-runs.
Weather
- Typical high: 15°C / 59°F · typical low: 5°C / 41°F.
- Light dropping noticeably — sunrise at 7:30 AM by month-end.
- First autumn cold fronts arrive in the last week.
Wind
Variable. The first three weeks are still relatively calm (afternoon gusts 20–35 km/h). The last week brings the first real autumn fronts and stronger winds. Pack a heavier wading jacket from mid-month.
Hatches & insect activity
Tapering on dry-fly water but still productive. Caddis still come off in the afternoon. Terrestrials decline. The sea-run fishing is a swung-streamer game, not a dry-fly game.
Best rod weights & lines
- 5-weight — the trout days early in the month.
- 7-weight — primary sea-run rod, Skagit head, T-11 sink tip.
- Switch rod 11'6" #7 — for swinging two-handed across the wider runs of the lower Serrano.
Best species & flies
- Sea-run brown trout: Conehead Bunny Leech size 2 and 4 (olive/black or all-black), Sunray Shadow, pink/black Intruder. The trophy fish of the season.
- Brown trout: still excellent through the first two weeks on the spring creeks.
- Coho salmon: first fresh fish in the estuary in the last week.
Notable events
March 8–28: peak sea-run window · our 21-pound 4-ounce sea-run came in this window in 2023. Average density of fresh fish in the lower Serrano peaks around the 20th. Booking demand for these three weeks is the highest of the year.
April · Closing.
April is the season's best-kept secret. Cold mornings, frost on the boat, fewer rods on the water, and the biggest fish of the year. Sea-run brown trout in the 12–20 lb class are landed every April. The coho run peaks. The fishing is harder than in February — and the fish are larger. The season closes on April 30.
Water level & clarity
Low and clear, with the first autumn rain events beginning to raise the lower Serrano in the last two weeks. The estuary is busy with coho and tail-end sea-runs.
Weather
- Typical high: 11°C / 52°F · typical low: 2°C / 36°F.
- Below-freezing mornings are routine.
- First snow of the new winter possible in the last week.
- Daylight back to 13 hours by month-end.
Wind
Variable but generally lighter than peak summer. The autumn fronts move through 3–5 day cycles — fish the days between fronts. Average afternoon gusts 25–40 km/h, but the calm windows between fronts can be glassy.
Hatches & insect activity
Minimal. A handful of cold-weather midges and the last spinner falls of the season. April is not a dry-fly month. Plan around swung streamers and stripped baitfish patterns.
Best rod weights & lines
- 7-weight — every sea-run day. Floating + T-11 sink tip.
- 7-weight switch — Skagit head, the way most sea-runs come.
- 8-weight — coho in the estuary, fast strip work.
Best species & flies
- Sea-run brown trout: trophy class. The largest fish of every season come in April. Black Conehead Bunny Leech size 2, dark Intruder patterns, pink/black for low-light.
- Coho salmon: peak. Clouser Minnow 2, Popsicle 1/0, Flash Fly.
- Resident brown trout: out at dusk for the last 90 minutes — biggest browns of the year.
Notable events
April 30: season close · the largest sea-run brown of 2025 (19 lb 8 oz) was landed on April 27, three days before the closer. Average cost per fish caught in April is the lowest of the year — fewer fish in the net per day, but heavier average weight. We block off the last week as a guides-only retreat.
Which month is right for you?
If you want dry-fly fishing
Book mid-January through mid-February. Stable weather, lowest winds, hopper season at full strength, the most willing surface fish of the year.
If you want the trophy sea-run brown trout
Book March 8 through March 28. The single highest-density sea-run window. Bring an 8-weight outfit ready to go.
If you want the most species variety
Book the second half of February. Rainbow trout, big brown trout, the first sea-runs, and the tail end of the king salmon — all in the same week.
If you want solitude and the largest fish
Book April. Cold mornings, fewer rods, the biggest brown trout of the year, and trophy sea-runs through the close. Pack serious cold-weather layers.
If you're a beginner
Book January. The longest days, the most willing fish, and the widest range of techniques to learn — from streamer work to dry fly to nymphing.
When-to-come questions, answered.
February is the single best month: most stable weather, lowest winds of the year, lowest water clarity, peak dry-fly hatches and the first sea-run brown trout entering the rivers in the last week.
March is a very close second for those targeting trophy sea-run browns. April is the season's best-kept secret for the largest fish of the year.
Yes. The Roaring Forties latitudes drive consistent westerly winds. November and December average 30–40 km/h afternoon winds with gusts to 70.
February has the calmest weather of the year — afternoon winds drop to 15–25 km/h. April is variable with cold fronts. Mornings before 11 AM are reliably the calm window every month.
Yes — and April is the most underrated month of the season. Cold mornings (often below freezing), fewer rods on the water, and the largest sea-run brown trout of the year.
Bring serious cold-weather layers (down mid-layer, heavyweight wading jacket, fleece-lined waders) and expect the season-best trophy fishing.
Bring a 5-weight for trout work in rivers and Spring creeks, a 6-weight as a do-it-all rod for streamers and bigger water, and a 7- or 8-weight for sea-run brown trout (March/April) and Pacific salmon (Jan/Feb).
A Skagit-style switch rod (11'6" #7) doubles as a sea-run swinging rod and is the single most versatile big-fish rod for this fishery.