How to Read Tide Charts

Do you want to score the best waves of your life? Then you need to learn to read tide charts. Being able to read a tide chart can make the difference between scoring the waves of your life and getting completely skunked, or even worse, dragged out to sea or plunged onto dry reef. Not having checked the tide is a beginner error you definitely want to skip!

WHAT IS A TIDE CHART

Tide charts are displays of tide data for a given date or set of dates. Fortunately we humans have become fairly good at predicting high and low tides accurately across the globe. Tide charts are readily available across the internet on surfing, fishing, and wind-related websites.

TYPES OF TIDE CHARTS

Tide charts come in three main forms:

1. Tables

2. Wave Graphs

3. Combination of the two

I will go over all three of them in order.

TIDE TABLES

A tide table merely plots out the dates and lists the high and low tides of each day. This is a screen grab from a tide table on CR Surf Dot Com. You simply look to the date or date ranges you’re planning to surf and then correlate the times with the tides. You’ll notice that each high or low tide moves up in time by about 45-55 minutes every day. This reflects the fact that the earth is constantly changing position as it orbits the sun. Tide tables are great because they have all the relevant information laid out right in front of you. You can look backwards in time to a day you had a particularly good or bad session and find out what the tides were doing. You can also use them to plan surf trips. For example if you find out that a certain place is only good for beginners at high tide and it’s a tropical destination with high heat midday, then you might want to plan your trip around an earlier morning high tide cycle. You may also want to factor tides into other important data points like favorable winds. If you’re planning to surf somewhere where the winds are usually only good at certain times of the day, then it would be ideal if you could plan for the ideal tides to also line up in that window.

wave graphs

This is a screen grab from Surfline.com, Long Beach, NY tides at time of writing. A wave graph gives you a visual sense of how full or empty the tide is at any given time. You can get more accurate data about heights in between peak tides. This is great to know if you’re really trying to dial in a spot. You can retroactively check what the tide was doing exactly when you had the best part of your session, and use this information to help plan future sessions. Surfline has a larger at glance wave graph tide calendar that you can access through their “tide calendar” widget. You simply enter a two week range into the search bar and it will pull up two weeks worth of tide data. Technically Surfline will give you both the wave graph and the tide table, so you are able to get the best of both worlds there.

HYBRID TABLE + WAVE GRAPH 

As for the third kind, the hybrid model, as I said, it is available on Surfline’s tide calendar widget. It’s also common in physical tide calendars you can buy to hang on your wall. This screen grab is from Tidelines.com, a company who can make custom tide calendars for your area. Another popular product that includes both wave graphs and tide tables is the tide journal or log. You can purchase one of these for your area on Tidelog.com. It’s a stellar idea to have a physical tide log journal so that you can write down the conditions you surfed on any given day. Of course you could also do this in any sort of e-journaling app. The upshot of the Tidelog is that you wouldn’t have to also source the tide data – it’s right there! The other great thing about this hybrid model is that it always displays the moon phases so that you can better correlate them with the tides.

moon charts

I also recommend downloading a moon phases app to your phone. Not every tide chart also lists the moon phases, and they’re worth knowing. Both the sun and the moon’s gravity have an effect on tidal cycles. During full and new moons we say that the earth is in syzygy, which means they’re all lined up. When they’re lined up that makes for larger differences in high and low tides. When they’re at right angles the sun is exerting a counter force to the moon and the tides are less extreme. If you want to learn more about this check out this blog post I wrote. That will help you understand more about how tides work and how to find out the best tides for surfing at any spot in the world.

additional considerations

We live in a technologically advanced age, and it’s possible to wear the tides on your wrist. In fact if you’re a surfer, sailor, or fisherman I would not even consider purchasing a wearable smart watch if it doesn’t have a tide function! I am a recent Apple Watch convert, and I love to be able to see the tides at a glance at all times. I do not, however, use the watch to forecast tides. For that I use tables and graphs online. 

In conclusion, it’s crucial that you learn to read tide charts so that you can be on the best waves for your level at all times. For example here is a picture of a low tide wave in SW Costa Rica near my property, Rancho Diandrew:

You can see the river mouth rocks exposed in front of the wave. It’s steep and fast and hollow, which is perfect for expert surfers. If you’re looking for tubes in this part of the world, then you need to target a low tide cycle in the mornings. For comparison here is a high tide wave in the same area:

Note how much softer and gentler and “fuller” this wave is compared to the low tide wave. If you’re visiting this area of the world and you’re just looking to cruise, you can find any high tide window to suit your fancy. If you want to surf higher tides and escape the midday heat, you’d want to look at a tide chart to find out when it will be high tide in the mornings. 

Remember that these are just examples from one part of the world. Tides work differently at every break. Fortunately tide data is available for every break! If you need any help planning a trip you can always book a Virtual Consult. I also go over tides extensively in my Online Forecasting Course.  

Thanks for reading. If you enjoyed this post please share it with friends via email and social media, and consider subscribing to my weekly Philo-surfy Zine at dr-dion.kit.com and to my YouTube Channel.

How Tides Affect Surfing and the Best Tides for Surfing

The first thing you need to know about how tides affect surfing is that while tides are a cosmological/global phenomenon, how they operate in terms of surf conditions varies widely from location to location. That said, it’s good to get some basic information down about tides before we move into determining “the best tides for surfing.” In what follows I’m going to lay out very basic tide science. Then I will tell you how to find out about tides for surfing in the area(s) you plan to surf. 

Fig. 1

Basic Tide Science

Fortunately we’ve been able to observe and measure the heavens and the oceans long enough to determine basic phenomena. This science continues to develop as we continue to make more observations and measurements. I say that to underscore that I am explaining the current scientific understanding. It has changed over time — we no longer think gods move the sun around the earth via charioteer — and it will likely change again.

Earth’s surface is 71% water and 97% of that is the ocean. It is the case that all of the earth’s physical stuff – rocks, magma, minerals – is moving in the broadest sense of movement, and all the stuff – water, gasses, air – moves at different rates. Water, it happens, is particularly moveable, sloshy stuff, and with all of this movement, well it sloshes a lot, except of course when it’s frozen (but we’ll table that for now). Ever sit in a bathtub and move a little and see the water sloshing up the sides of the tub? Or try to carry an overfull cup of coffee across a crowded cafe and not try to spill any on your shoes as it sloshes over the rim? Or what about when you sit down to drink the coffee and it’s really hot and you blow your breath over the top and watch it ripple, effectively moving the coffee (which is just caffeinated water) within the cup? On the most basic of basic levels tides are a manifestation of the sloshing caused by the overall relationship of the earth, moon, sun, and the rest of the cosmos, in addition to the various factors that affect the water on earth itself. 

It is common to think of the cause of this sloshing as “gravity.” And for now you can think of it that way. There’s a little more to it than that, and we can nerd out on that at a later date. For now let’s just use the common notion of gravity. The moon rotates around the earth and the earth/moon combo rotates around the sun. Because the moon is closer to the earth and its orbits are tighter it exerts more force or pull, which creates essentially two large bulges of water on either side of the earth. In its daily rotation, the earth basically moves into and out of these bulges (see Fig. 1).

So the sloshing can be thought of both as the water being pulled and pushed and as the earth moving into areas of higher and lower water. The push and pull from the moon — the bulges —, however, remain relatively constant. The bigger factor in determining general, global tide size is . . . The sun!!! Whhhaaaat?! Yeah, I know, you didn’t read that on any surf website yet, right? Well, it’s true. The sun’s gravitational pull has a larger effect on how high and low the tides are than the moon’s does. 

Fig 2.

In Fig. 2 you can see what we call syzygy. Syzygy is two Greek words — syz from syn — which means “with” — and gy from ge — which means “earth.” So syzygy is when the moon and the sun are lined up with earth. This creates both full and new moons, and on full and new moons we have what are called spring tides. Remember that the bulges of water created by the moon are always there, so when it’s lined up with the sun you get that extra bigness from the sun’s gravitational pull. All you need in order to find out whether the tides are spring, is a moon calendar. If it’s full or new you can bet the high tides will be higher than usual. And that’s another key. It’s not that the tides are more extreme, per se, but that the highs are significantly higher. What does that mean for surfing? Just that however the place you’re planning to surf reacts to high tide, it will have that reaction even more when it’s a full or a new moon.

Fig. 3

In Fig. 3 the moon, sun, and earth are not in syzygy. This is when the sun’s gravitational pull is not lined up with the moon’s. This creates what are called neap tides. True neap tides are, as the picture shows, when the sun and the moon are at about a right angle from one another. In this time of the lunar/solar cycle, the sun exerts a counteracting force on the moon. The bulges are smaller and the tides are overall lower. What does this mean for surfing? You can expect a smaller tidal swing overall, and for the lowest tides to be during a neap cycle. So, if the place you’re planning to surf is affected (for better or worse) by low tides, you can expect those lows to be lower during neap tides.

Types of Tides

Diurnal Tides

Diurnal tides happen only 2x a day, i.e., there is only one high and one low tide in a 24 hour period. These change in approximately 50 minute increments in a 24 hour cycle. If it was low tide at 6a on Monday, it will be high tide at 6p that same day. On Tuesday the low tide will be roughly at 6:50a and on and on.

Fig. 4: Diurnal tides near Perth, Western Australia

Semidiurnal Tides

Semidiurnal tides happen 4x day, i.e., there are two high and two low tides in a 24 hour period, alternating about 1x every 5 hours and 50 minutes, and shifting up an hour each day. So if it was low tide at 6a on Monday, it will be high tide around 11:50a that day, low tide again around 5:50p, and high again around midnight. The next low tide will move be around 7a on Tuesday and so on.  Semidiurnal tides can be equal or unequal.

Semidiurnal equal Tides

Both low tides and high tides in a given 24 hour period are similar heights. That is to say, the heights of each high are nearly equal, and the heights of each low are nearly equal. NY/NJ is an example of semidiurnal equal tides:

Fig. 5: Semidiurnal equal tides in Rockaway Beach, NY

Semidiurnal unequal tides

The two low and two high tides in a given 24 hour period are are unequal. That is to say, there will be a much larger difference in the heights of the two highs and the heights of the two lows. The CA coast provides a textbook example of semidiurnal unequal tides:

Fig. 6: Semidiurnal unequal tides in Southern CA

Slack tide

Also known as “the top of the tide.” This is when the tide is at peak high or low and is neither moving in nor out. At many surf breaks the waves can go dead during slack tide (not everywhere at all times, but if you’re wearing a tide watch and you notice that a long lull corresponds to the peak tide, that’s a slack tide). 

Outgoing tide

This is when the tide has hit peak high, gone through the slack period, and is now “moving back out.” In some surf breaks outgoing tide can dampen swell coming in. In others it can drain just enough water off of the bottom to make it possible for waves to break. 

Incoming tide

This is is when the tide has hit peak low, gone through the slack period, and is now “coming back in.” In some cases an incoming tide can increase swell height. It is not the case that all breaks are better at incoming tide. Nor is it the case that incoming tide generates swell on its own. There has to be swell already in the water (generated by winds much further out to sea) in order for incoming tide to be of any help at all in terms of creating waves when there previously were none or very few or in making an already existing swell a few feet larger (creating an additional “pulse” in the swell). 

King Tides

Fake news. According to NOAA, a king tide is a non-scientific term used to describe exceptionally large tides, which are more accurately described as spring tides (see Fig. 2), and occur during full and new moons and when the sun and the moon are closest to the earth (perigee). King, or more accurately, spring tides simply make the high tides higher. This can be good or bad depending on the break you’re surfing. The water will be deeper and closer to shore (see video above).

So what is the best tide for surfing?!

Based upon this very basic outline of the tides, the best tide for surfing varies location to location. Put differently, there is no best tide for surfing. Do not trust or believe any website, instructor, coach, or pamphlet that says one tide is best across the world. It’s simply not the case. If we took a survey of all the world’s surf breaks, we might find that overall mid tides (neither too high nor too low) have a slight advantage over all other tidal possibilities, but that would still be mere conjecture.

What Else Do I Need to Know About finding the best Tides for surfing?

I will cover all of these in greater depth in future articles, but here’s the general outline:

1. How to read a tide chart

2. How to access both general and local knowledge about what tides work best at the various breaks in a given area — start with general knowledge via the internet (websites like Surfline.com), but refine that knowledge once you get to your destination by asking locals, pros, and coaches

3. Determine what kind of bottom you’ll be surfing over. Here are your options: 

• Beach break — sand w/out jetties 

• Beach Break — sand w/jetties 

• Sand point break 

• Rock reef point break 

• Rock reef 

• Coral reef 

• Cobblestones

• Mixture of sand and rock 

• Mixture of sand and coral 

• Mixture of sand and cobblestones 

I hope you find this post useful. If you’d like to set up a consultation to determine what tides are best at a break you plan to surf, sign up HERE. If you want to know more about how tides interact with all of the other surfing variables, take my forecasting course HERE. If you’re interested in optimizing all aspects of your surfing experience, sign up for a surf journey consultation HERE. Remember to check out my YouTube channel and my online digital products and courses!

further reading

Tides: The Science and Spirit of the Ocean (2017) by Jonathan White

Waves and Beaches (2021) by Kim McCoy and Willard Bascom

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