How to Read a Surf Forecast: Your Guide to Catching Better Waves in Bali
- Nicole Auf der Maur
- Apr 8
- 3 min read
Surf forecasts can look overwhelming at first—but understanding them can seriously level up your sessions. This guide breaks it all down, whether you’re catching your first wave or chasing clean conditions.
Since Surfline is our go-to, we’ll be using it as the main example to help you get familiar with reading surf forecasts.
The Tide Chart: Why It Matters
Tides affect where, when, and how a wave breaks—so checking the tide for your chosen spot is just as important as checking swell and wind.
In Bali, not all surf spots work the same way—and tide plays a huge role in when a break will be at its best (or worst). Because the island is full of different types of surf spots—like beach breaks, reef breaks, and point breaks—each one responds differently to the rise and fall of the ocean.
Low Tide: Waves break faster and hollower—good for advanced surfers, but risky for beginners due to exposed reef or rocks.
Mid Tide: Often the best all-around. Enough water for safety, while still keeping good wave shape—great for most Bali breaks.
High Tide: Can make waves soft or slow, but some reef spots only work well with the extra water.
Let’s Break It Down Using Batu Bolong, Our Home Spot
Mid to high tide is usually best for most surfers—especially beginners—thanks to its softer, more forgiving waves. On lower tides, the wave tends to break faster and can be more technical, making it better suited for confident or advanced surfers.
Daylight (white area): 6:02 AM to 6:42 PM.
High tide: 7:51 AM
Low tide: 1:27 PM
Best Surf Times, 8.4.2025:
In general, mornings offer cleaner waves thanks to lighter winds—so it’s best to surf before the afternoon breeze kicks in.
For Beginners:
9:00 – 11:00 AM,
4:00 – 6:00 PM
These windows are around mid to high tide, offering soft, rolling waves that are ideal for learning.
For Advanced Surfers:
12:00 – 3:00 PM
The dropping tide brings faster, hollower waves—more suitable for experienced riders looking for a challenge.
Keep in mind—the tide shifts a little each day, so the ideal surf window won’t always be at the same time.
Understanding Wave Height
Most modern surf forecasts—like Surfline—measure wave height by the face of the wave, which is the part you actually ride. This refers to the vertical distance from the trough (bottom) to the peak (top) and is usually shown in feet or meters.
Wave Size Guide by Skill Level
Beginners: 1 – 4 ft (0.3 – 1.2 m)
Soft, rolling waves that are easier to paddle into and less intimidating.
Intermediate Surfers: 2 – 4 ft (0.6 – 1.2 m)
More power and shape—great for practicing turns, positioning, and timing.
Advanced Surfers: 4 ft+ (1.2 m and up)
Bigger, steeper waves that require stronger paddling, faster reflexes, and more confidence.
What the Wave Size Means for Batu Bolong – April 8, 2025
Morning: 1.2 – 1.5 m
Noon to Afternoon: 0.9 – 1.4 m
The waves are fairly large for beginners—challenging but manageable for intermediates in the morning, and a good opportunity for more advanced surfers looking for a bit more power.
Primary vs. Secondary Swell
When you open a surf forecast, you'll usually see more than one swell listed—Primary Swell, Secondary Swell, sometimes even a third or fourth. But what do these actually mean?
Primary Swell
This is the dominant swell, and it’s the one with the highest potential to hit your coastline with the most energy. It usually has the largest wave height and the longest period, meaning it carries more power and creates the most surfable waves.
Think of it as the "main act" in a concert—it sets the tone for your session.
Secondary Swell
The secondary swell is like a background rhythm. It still reaches the coast, but with less energy than the primary. It might come from a different direction, have a shorter period, or be generated by a different storm system entirely.
While it's not as powerful, the secondary swell can influence wave quality—sometimes for better, sometimes for worse.
More coming your way—stay tuned!
Up next: Swell Period, Swell Direction, and Wind—three key factors that can make or break your session.
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