Gulf of Thailand — May 2026 Report
As May advances and the Andaman Sea progressively closes to offshore fishing, the Gulf of Thailand steps forward as the country's primary saltwater option. This isn't the Gulf settling for second-best status — it's a coast that operates on its own timetable, sheltered from the southwest monsoon by the spine of the Thai-Malay Peninsula and offering genuine pelagic fishing through conditions that shut down operations on the other side entirely. In May 2026, the Gulf delivered on its transitional-season promise, with strong action on mid-range pelagics out of Pattaya, productive fishing across the southern Gulf near Koh Samui, and squid jigging reaching something close to its annual peak.
Weather and Water
The Gulf's unique geography — protected from the Andaman by the peninsula and open to the northeast — means the southwest monsoon affects it differently and with considerably less force than the Andaman coast. May on the Gulf is warm and often humid, with patchy afternoon thunderstorms and occasional squalls, but the sea state remains manageable for offshore operations on most days. Surface temperatures climbed through the high 20s Celsius across the central Gulf, which suited the pelagic species that were the primary target for charter fishing this month.
Visibility varied across the Gulf, with the areas around offshore platforms and wrecks maintaining cleaner water than the river-influenced coastal margins. Baitfish concentrations built noticeably through the month, tracking along current edges and temperature breaks, and wherever bait concentrated, pelagics followed.
Longtail Tuna and Spanish Mackerel
Longtail tuna were the workhorses of the May Gulf report. Schools were consistently located on structure and current breaks at mid-range offshore distances from both Pattaya and the Samui grounds, and charter vessels targeting them with trolling rigs and cast lures found reliable action through most of the month. The fish weren't large by international standards — Gulf longtails typically run between two and six kilograms on most outings — but they are among the most aggressive and acrobatic sportfish available in Thai waters, and on light to medium tackle they account for some of the year's most entertaining Gulf sessions.
Spanish mackerel appeared alongside longtails in mixed schools and around offshore reef structure and wrecks. They were less consistently predictable than the tuna but produced some of the month's most exciting fishing when encountered — fast, decisive strikes on trolled skirts and high-speed metal lures, with fish in good condition from a season of feeding on Gulf baitfish.
Squid jigging boats working the central Gulf banks through the first two weeks of May reported some of the most consistent night action seen in that area this season.
Cobia and Offshore Structure
Cobia showed at several of the Gulf's offshore platforms and artificial reef structures, with the areas around decommissioned and active petroleum infrastructure proving particularly reliable. These fish are reliable May performers on the Gulf — they arrive ahead of the full monsoon, feed aggressively on structure, and respond to both lure and live-bait presentations. Reports from charter vessels running Pattaya's offshore platforms mentioned cobia encounters on most structure-fishing trips through the first three weeks of the month.
Queenfish were active along the inshore coastal margins, particularly around river mouths and estuary edges on the rising and falling tide. Light spinning tackle and slim metal lures or surface stickbaits produced well for anglers targeting them specifically, and the queenfish's speed and leaping ability make it a genuine highlight species for anglers who don't know it yet.
Squid Jigging — A May Highlight
May is arguably the best month for squid jigging on the Gulf of Thailand, and 2026 reinforced that reputation. Light boats anchored over sandy-bottom grounds through the night — their powerful raking lights drawing zooplankton, which draws baitfish, which draws squid — produced consistent catches of bigfin reef squid on both dedicated squid jig rigs and simple sabiki-style offerings. The central Gulf banks and the grounds south and east of Koh Samui were both productive, with the Samui grounds benefiting from cleaner blue-water intrusions that concentrated squid densely.
For visiting anglers unfamiliar with Gulf squid jigging, the experience is more accessible than it might sound — it's not technically demanding, the equipment is inexpensive and widely available, and the results can be spectacular. Many charter vessels that run daytime pelagic trips also offer evening squid jigging packages that make for an excellent two-session day.
If you book a dedicated squid jigging night on the Gulf, pack warm layers — even in May, several hours on a boat in the dark on open water can feel surprisingly cool compared to the daytime heat onshore.
Koh Samui and Southern Gulf
The southern Gulf grounds accessible from Koh Samui produced solid mid-pelagic fishing through May. Yellowfin tuna, in numbers that the central and northern Gulf rarely sees, appeared on deep-water structure in the southern grounds, and charter vessels working these areas logged multiple encounters through the month. Fishing in the southern Gulf tends to involve longer runs from port, but the species diversity and the quality of the fish make the transit worthwhile for serious offshore anglers.
The charter scene operating out of Koh Samui is smaller and more specialized than Pattaya's, but experienced guides working the southern grounds know where the fish are and run well-equipped vessels suited to the longer offshore distances involved.
Pattaya Charter Scene
Pattaya remained the Gulf's most active charter hub through May, with its proximity to Bangkok making it the default choice for visiting anglers on short schedules. The majority of May fishing trips out of Pattaya focused on the mid-range offshore grounds — distances of 30 to 60 kilometers — where pelagic species and structure fishing produced the most consistent results. Inshore fishing around the Pattaya coastal islands continued to offer options for anglers with less time or less interest in long offshore runs.
Looking Ahead to June
June on the Gulf shifts the balance further toward squid jigging, inshore, and structure fishing as the monsoon consolidates. Pelagic fishing continues but becomes less consistent in the central Gulf as current patterns shift. The southern Gulf, particularly around Koh Samui and Koh Tao, tends to maintain better pelagic conditions later into the monsoon season than the central and northern Gulf. Squid jigging will be excellent through June and July, making the Gulf a solid monsoon-season destination for anglers willing to adapt species targets.
Recommendations for Visiting Anglers
May is an excellent time to experience Gulf fishing — conditions are good, species variety is high, and the contrast with the closing Andaman season makes the Gulf feel particularly alive. Target longtail tuna and Spanish mackerel for the most reliable action, add a squid jigging evening to any multi-day trip, and don't overlook cobia around offshore structure. Book through the established charter operators at Pattaya or Koh Samui, confirm sea conditions with your captain before departure, and bring medium-weight spinning or casting gear suitable for the full pelagic range.
