As the dust settles on the bustling high season and the first tropical rains of May begin to cool the Central Pacific, a transformation occurs beneath the surface of the waters off Jaco and Los Sueños. While the “Dry Season” (January through April) is world-renowned for high-volume Sailfish releases, seasoned anglers know that May marks the start of the heavyweight season.
This is the beginning of the “Green Season” in Costa Rica—a time when the crowds thin out, the landscape turns a vibrant emerald, and the legendary Blue Marlin begins its summer dominance.
The May Pivot: Why Now is Marlin Time
For many, the mention of “rainy season” suggests a time to stay indoors. In the Central Pacific corridor of Costa Rica, however, the “Green Season” is a tactical advantage for sportfishing. The arrival of May brings two critical factors for billfish: Debris Lines and Cooler Surface Temperatures.
The initial rains wash logs, branches, and organic “trash” from the river mouths into the ocean. These currents create natural FADs (Fish Aggregating Devices). Smaller baitfish, such as Bonito and small Mahimahi, congregate under these floating structures. For a hungry Blue or Black Marlin, these debris lines are essentially a buffet line.
Species Spotlight: What’s on the Line in May and June?
1. The Blue Marlin (The Summer King)
Starting in May and peaking through August, Blue Marlin activity in the Central Pacific skyrockets. Unlike the smaller Striped Marlin seen in the winter, these “Blues” are built for power. If you are hunting for a 300lb+ fish, the summer months out of Los Sueños are your prime window.
2. The Black Marlin
Black Marlin are often found closer to the reefs and seamounts than their Blue cousins. As we move into June and July, the Black Marlin activity increases, particularly around the famous “corner” of the Continental Shelf.
3. Pacific Sailfish (The Transition)
While the “peak” numbers of 20+ releases a day might have dipped since March, Sailfish are year-round residents here. In May, you can still expect consistent action, often finding them in the same current seams as the Marlin.
4. The "Bonus" Yellowfin Tuna
The Green Season is synonymous with “Tuna Time.” Large pods of Spinner Dolphins often move through the Jaco area during the summer months, and beneath them, you will find the 100lb+ Yellowfin Tuna. Targeting Tuna in May is a high-octane way to round out a Billfish expedition.
Regional Breakdown: Why Jaco/Los Sueños Wins in Summer
While the North Pacific (Guanacaste) experiences heavy “Papagayo Winds” earlier in the year, the Central Pacific stays relatively calm. However, by May, the North begins to see better fishing, while the South (Golfo Dulce) enters a very wet period.
Jaco and Los Sueños sit in the “Sweet Spot.” Our geography provides a protective buffer that keeps the morning seas “greasy calm,” even as the summer heat builds. This allows our captains to make long runs to the seamounts—the offshore “mountains” where the monster Marlin hunt—without the brutal chop found in other regions.
Tactical Advice for the Green Season
To maximize your 2026 trip, keep these three professional tactics in mind:
- Early Starts: The classic tropical pattern involves clear, calm mornings and afternoon showers. We push our boats out at dawn to capitalize on the 6:00 AM to 1:00 PM window when the sea is like a mirror.
- The “Trash” Search: Don’t ignore the floating logs. Some of the biggest Marlin strikes happen within 50 yards of a floating branch.
- Live Baiting: While trolling lures is effective for covering ground, May is a fantastic time for “slow-trolling” live Bonito. There is nothing more heart-pounding than watching a 400lb Marlin crash a live bait just 30 feet behind the transom.
Planning Your Expedition
If you are aiming for a “Grand Slam” (catching three species of billfish in a single day), May through August offers one of the most realistic windows to achieve it. The diversity of the water right now is at a seasonal high.
While the general calendar offers a baseline, mastering the costa rica billfishing season requires a crew that understands how to read the complex blue-water transition zones of the Central Pacific. In the high-stakes world of offshore expeditions, the difference between a dry day and a Grand Slam often comes down to local scouting and technical precision.
For those looking to push even further offshore, our Guide to FADs and Seamount Fishing breaks down the high-tech tactics we use to target monster Marlin at the underwater mountain ranges. If you’re still planning the logistics of your stay, check out our comprehensive breakdown of Jaco Beach Sportfishing and Charters out of Los Sueños to coordinate your transport and marina arrival.
Frequently Asked Question for Billfishing in Costa Rica
Q: When is the best time to catch Blue Marlin in the Central Pacific?
A: While Marlin can be found year-round, the primary peak for Blue and Black Marlin in the Central Pacific runs from May through August. During this “Green Season,” the arrival of debris lines and cooler water temperatures brings heavy-hitting billfish closer to the coast of Los Sueños and Jaco.
Q: Does the rainy season affect fishing quality in Costa Rica?
A: Paradoxically, the “Green Season” rains often improve fishing quality. The afternoon showers create temperature breaks and wash natural logs into the sea, which act as fish-aggregating devices (FADs) that attract baitfish and large pelagic predators like Marlin and Tuna.
Q: Can I catch a "Grand Slam" during the summer months?
A: Yes. The summer window from May to August is one of the most consistent times to achieve a Grand Slam (catching three different billfish species in one day). The overlap of resident Sailfish with the peak migration of Blue and Black Marlin creates the ideal conditions for multi-species success.
Q: Are the seas rougher during the costa rica billfishing season in the summer?
A: Generally, no. In the Jaco and Los Sueños region, the morning seas from May through August are typically very calm, often referred to as “greasy.” While tropical rain is common in the late afternoon, the early-day conditions are perfect for long offshore runs to the seamounts.
Ready to secure your dates? Book your next Costa Rica Sportfishing Charter with Jaco360 and hunt the giants of the deep.
Jaco Beach, San Jose Costa Rica
+01 506 8302 4168 (Phone or WhatsApp)
info@jaco360.com
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