April is Thailand's most extreme month. The cool northeast monsoon is a memory. The southwest monsoon is still weeks away. In the gap between the two, the country bakes. Bangkok regularly reaches 38–40°C. The Andaman coast bakes under pre-monsoon pressure. The Gulf continues quietly, as it always does. And the pay-lakes around Bangkok are still fishable — but only if you operate by a strict dawn-or-nothing rule.
This is not the easiest month to fish Thailand. It is, however, a perfectly viable one if you approach it with the right expectations and the right schedule.
The Weather and Water This Month
April is the hottest month in central and northern Thailand. Bangkok and the central plains see average highs of 35–38°C, with heat index values pushing well beyond 40°C in the afternoon. Humidity is rising as the pre-monsoon atmosphere builds moisture. Occasional intense thunderstorms break the heat in the late afternoon or evening — relieving to experience, inconvenient for fishing.
Rainfall is still relatively low by monsoon standards, but isolated afternoon storms become more frequent through the month, particularly after the 15th. Lightning risk is real and should be factored into outdoor session planning.
Mid-month brings Songkran — Thailand's new year water festival — typically falling on April 13–15 and extending to a full week in many regions. Bangkok becomes a water-fight arena. Roads are congested, public transport is disrupted, and reaching pay-lake venues during Songkran week requires more patience than usual. Many Thais visit family in provincial areas during this period, which can actually thin Bangkok lake crowds slightly even as the capital celebrates.
The Andaman coast is hot, increasingly humid, and beginning to build the pre-monsoon swells that signal the impending season change. Seas are still manageable in early April but become less reliable by month's end.
Songkran planning
If you're in Bangkok during Songkran week, plan your fishing for early morning — 5:30 to 10 a.m. — and be off the water before midday. Afternoons in Songkran week are both hot and chaotic, especially in transit.
Freshwater Fishing This Month
Bangkok Pay-Lakes — Dawn Fishing Only
The Bangkok pay-lake circuit does not close in April. It adapts. Experienced local anglers — Thai and expatriate alike — have long since abandoned any romantic notion of afternoon sessions. In April, you fish from first light and you are finished before the sun climbs high enough to make the bank feel like a concrete oven.
The window that works: arrive at 5:30 to 6:00 a.m. Fish hard through the cool morning. By 10 a.m. the heat is asserting itself. By 11 a.m. you are looking for shade. By noon, only the most committed anglers remain, typically sheltering under umbrellas and questioning their life choices.
Bungsamran Lake is worth early April mornings. Giant Mekong catfish and giant Siamese carp feed actively in the cooler dawn water. April water temperatures in Bungsamran's shallower areas can already be touching 30°C by midday. The fish know this and front-load their feeding accordingly.
IT Lake Monsters is similarly productive in the early hours. Arapaima are surface-oriented and visible on April mornings, rolling in the low-oxygen-stress conditions that warm, still water creates. Surface presentations — large poppers or slow-retrieved rubber fish — can be surprisingly effective.
Dreamlake Fishing Resort, Bang Na Lakes, and Boon Mar Ponds all operate through April and are worth visiting if you want shorter drives from central Bangkok or prefer a quieter setting than Bungsamran on a busy holiday week.
Giant snakehead fishing in Bangkok's canals reaches a productive phase in April. Snakehead are tolerant of warm, low-oxygen water by biology — they can breathe atmospheric air. Pre-dawn and dawn surface fishing for snakehead in the klong system can be spectacular in April, before other anglers are even awake.
Northern and Highland Areas
April is not the time for serious northern reservoir excursions. Water temperatures in highland lakes have risen substantially, clarity has diminished in many systems, and the mahseer fishing that was so rewarding in January and February has faded to a minor-key opportunity at best. If you find yourself in Chiang Mai in April, the city has considerable appeal, but don't build your trip around the fishing.
Gillhams Fishing Resort in Krabi continues to operate, though its managed lake sees rising temperatures. Freshwater sessions here are best in the early morning. The afternoon is better spent at the beach.
April in Bangkok rewards the 5 a.m. alarm and punishes the angler who sleeps in.
Saltwater Fishing This Month
Andaman Sea — Winding Down
The Andaman's high season is closing. Most reputable charter operators running long-range liveaboards to the Burma Banks and Similan Islands have scaled back or ceased operations by mid-April. A handful continue into early April under what the industry terms "late season" conditions — seas are still fishable but less predictable, and pre-monsoon squalls are a realistic daily possibility.
Day charters out of Phuket and Krabi continue operating through April, typically targeting inshore reefs where conditions are more manageable than open water. Racha Yai and Racha Noi remain accessible on calm days for GT and reef species. Phang Nga Bay offers sheltered inshore water that fishes well year-round; April is a good month for exploring its mangrove creek systems for barramundi and snapper.
The Similan Islands national park typically closes to visitors for its seasonal maintenance period around mid-April or May 1 — confirm exact dates with operators before booking anything that depends on Similan access.
For those committed to Andaman billfish, early April is the absolute last realistic window. Sailfish numbers drop sharply from March's already-declining figures. If you haven't fished the Andaman for sailfish by early April, the calendar has moved on.
Gulf of Thailand — The Reliable Option
The Gulf of Thailand is April's most consistent saltwater option. Koh Samui, Koh Tao, and the Chumphon area see stable, warm, calm conditions through most of the month. Barramundi, grouper, and Spanish mackerel fishing remains solid. Occasional pelagic runs — wahoo and mahi-mahi — reward trolling anglers who put in the distance from the coast.
Top Cats Koh Samui runs through April without seasonal interruption. The Gulf doesn't have the Andaman's dramatic billfish fishery, but its consistency in April — when the Andaman is winding down and the monsoon hasn't yet complicated anything — makes it the sensible choice for anglers planning salt-water trips this month.
The Gulf of Thailand fishing guide covers the region's species and techniques comprehensively.
Recommended Trips This Month
1. Bangkok Dawn Pay-Lake Sessions — Two or three early-morning sessions at Bungsamran Lake or IT Lake Monsters, starting at first light, finishing by 10 a.m. Perfectly viable in April if timed correctly.
2. Gulf of Thailand from Koh Samui — Base at Koh Samui, spend two days fishing the Gulf with a local operator for barramundi, mackerel, and reef species. The Gulf is stable, operators are available, and island life provides ample non-fishing relief during the hot afternoon hours.
3. Phang Nga Bay Inshore Charter — Book a morning-only inshore charter in Phang Nga Bay targeting mangrove creek barramundi and snapper. The sheltered bay fishes well even as the outer Andaman becomes unpredictable. Return to Phuket for the afternoon.
4. Songkran Weekend Snakehead Session — If you're in Bangkok for Songkran, fish the klong system for giant snakehead at 5:30 a.m. before the city wakes up and the water fights begin. A uniquely Bangkok experience.
What to Avoid This Month
Avoid midday and afternoon outdoor fishing sessions anywhere in central Thailand. The heat between noon and 4 p.m. in April is not simply uncomfortable — it's potentially dangerous if you're exerting yourself in direct sun without adequate water and shade.
Avoid booking Andaman liveaboards without checking whether operators are still running. Many close between March and October. Those that continue into late April are operating at reduced frequency and with weather caveats. Read cancellation policies carefully.
Don't visit northern Thailand primarily for fishing. April is a beautiful month in Chiang Mai culturally, and Songkran celebrations in the north are vivid and memorable. But the fishing is a shadow of what it was in January.
Comfort and Gear Notes
April demands serious heat management. Sun protection clothing is not optional. A quality UPF 50+ sun shirt, buff covering neck and lower face, and a wide-brimmed hat are minimum requirements for any time on the water. High-SPF sunscreen applied every ninety minutes is standard practice.
Hydration is the critical variable. Bring at least two litres of water per person for a four-hour morning session, more if you're on the water under sun. Signs of heat exhaustion — nausea, dizziness, headache — should be taken seriously. Fish early, drink constantly, retreat to shade at the first sign of discomfort.
For Bangkok pay-lakes, the pay-lake etiquette Thailand guide is worth revisiting if you want to make the most of your morning hours without fumbling through venue logistics.
Where to Go Next
May brings the southwest monsoon's arrival and a fundamental shift in what's possible. The Andaman closes properly, Bangkok's pay-lakes settle into a quieter off-season rhythm, and the Gulf continues steadily. See our May fishing guide for how the transition plays out.
For context on the comfortable conditions that preceded this month, see March. And if you're planning around the monsoon, the monsoon season fishing strategy guide is the essential reference.
