The Peak Arrives
There is a specific quality to the Andaman in January that anglers who have fished it once find very difficult to forget. The air is dry and cool, carrying none of the tropical weight that characterises the rest of the year. The water is at its clearest and coldest of the season — still a perfectly comfortable 26 to 28 degrees at the surface, but cool enough to anchor baitfish schools in the upper water column and concentrate the predators that feed on them. And the sailfish are here, in numbers that justify every booking decision that was made months ago.
January is the month that the Andaman's reputation is built on. The sailfish grounds off the western coast, from the waters south of Koh Rok all the way north to the edges of the Similan chain, hold fish in densities that are genuinely exceptional for the region. On the good days — and in January the good days are not rare — multiple sail encounters are a reasonable expectation, not a best-case hope.
Weather and Sea Conditions
The northeast monsoon delivered its most settled performance of the season through January 2026. Winds were light and predominantly from the north-northeast, with the typical January pattern of calm mornings giving way to a light afternoon breeze that actually improves kite-fishing conditions by providing just enough wind to fly a productive presentation. Swell remained minimal throughout most of the month.
Water temperatures sat in the 26–28°C range at the surface, with a well-defined thermocline establishing at 20–30 metres depending on location. The thermocline is important in January — it effectively stacks baitfish in the warmer surface layer and concentrates feeding sailfish in water shallow enough to sight-fish on calm days. Water clarity was outstanding, with blue water pushing significantly closer inshore than typical for this coastline.
January's thermocline is as much a tool as a condition. When you find bait schools stacked near the surface — visible on the sounder and often confirming themselves with diving birds — you are almost certainly within striking distance of sailfish. Work that water thoroughly before moving on.
Sailfish: Peak Numbers on the Grounds
Reports from the sailfish grounds through January confirmed what the December trend had promised — the fish are at peak season density and they are eating. Captains working the traditional grounds between Phuket's west coast and the waters around Koh Rok reported consistent sail activity throughout the month, with kite-fishing producing the highest conversion rates on calmer days.
The Koh Rok grounds deserve the attention they reliably receive. The current edges and bait concentrations around this southern archipelago historically produce the most fishable sailfish aggregations of the season, and January 2026 was no exception. Multiple encounters per session were achievable on the better fishing windows, with the fish showing as free swimmers in the clear water and responding aggressively to a well-presented live bait.
January sails are in their best condition of the season — fat from months of feeding on the baitfish schools that the northeast monsoon pushes inshore. A hooked fish in January fights differently to one in March; the runs are longer, the jumps higher.
Marlin — mainly black marlin and the occasional blue — made predictable appearances on the trolling grounds through the month, primarily as bycatch for boats targeting sails on artificial lures. The presence of marlin on the grounds in January is not unusual and adds to the sense that the Andaman in its peak month offers a genuinely world-class pelagic fishery.
GT Popping: Still Strong, Still Consistent
January does not diminish the GT fishery — if anything, the continued clear water and settled conditions make popping more enjoyable and more productive. Koh Bon remained the standout venue, with the reef holding fish throughout the month and the surrounding water clean enough on most days to sight-cast to GTs moving across the shallower reef flats.
The Surin group — specifically the reef systems within the Surin Marine Park — was producing solid popping action for liveaboard crews who incorporated a day on the popping grounds into their northern circuit. Fish sizes were generally consistent with the December reports, with a higher proportion of larger individuals appearing through the cooler water of mid-January.
In January, look for GTs cruising in packs of two to five fish over shallow reef ground in the clearest water. In these visibility conditions you can position ahead of a moving group and cast into their path — one of the most exciting presentations in saltwater fishing and one that January's clarity makes possible.
Jigging: Dogtooth Tuna in Form
The deep-water pinnacles of the Similan group and the northern seamounts continued to produce well for jigging crews through January. Dogtooth tuna were the primary target and the primary result — fish holding at depth in the cleaner water and responding to both speed-jigging and slow-pitch presentations. The dogtooth fishery on these grounds is one of the Andaman's undersold attractions and January's settled conditions make reaching the deeper marks straightforward.
Liveaboard operators who scheduled early-morning jigging sessions before the wind built were consistently reporting the most productive results. The fish tend to be more active in low light and the absence of current when the tide is slack provides a window for getting jigs to the bottom at the desired angle.
Liveaboards: The Busiest Month
January 2026 saw liveaboard manifests at full capacity across the season's established operators. The northern circuit — Similan Islands, Koh Bon, Koh Tachai, Richelieu Rock, Surin group — was running seamlessly in the stable weather, and trip reports filtering back to the shore were uniformly positive.
For anglers planning January liveaboards in future years, the single most important piece of advice is to book early. Quality berths on the established liveaboard operators for peak-season January depart from available to sold out faster than any other month on the Andaman calendar.
February Outlook
The sailfish peak that January delivered continues seamlessly into February, which historically rivals January for the density and consistency of the offshore sail action. Conditions remain excellent — the northeast monsoon does not weaken meaningfully until late February or early March. For anglers who could not secure a January berth, February offers an equally compelling window.
Read our full sailfish season Thailand guide and Koh Rok sailfish article. For liveaboard planning, see our liveaboard operators Thailand overview.
