Spring and Neap Tides: Why the Week You Choose Matters

This is written to be used rather than admired. Each section below is a decision about the spring and neap tidal cycle, and each one has a default.

What drives the cycle

The sun and the moon both raise tides, and their relative positions decide whether those effects add together or partly cancel. When they align, around new and full moon, the two pulls reinforce and produce the largest range, which is called a spring tide. When they are at right angles, around the quarter moons, the effects partly cancel and the range is smallest, which is a neap tide.

The cycle therefore repeats roughly every fortnight and is entirely predictable years in advance. The word spring here refers to the water springing up rather than to the season, which confuses people constantly.

What changes on the ground

A spring tide uncovers far more of the lower shore, which is when rock pools, causeways and offshore features become reachable. It also floods higher, which is when quaysides overtop, low coastal roads flood and beaches disappear entirely at high water. Neap tides give a narrow band of movement, so the beach stays roughly the same size all day and the water never goes far out.

On a large-range coast the difference between the two is dramatic and completely changes what a place looks like. On a small-range coast, such as much of the Mediterranean, the whole cycle is barely noticeable.

Currents follow the range

A bigger range means more water has to move in the same six hours, so tidal streams run faster on springs than on neaps. That matters enormously for swimming, kayaking and small boat trips through narrows and around headlands. Slack water windows are shorter on springs, which reduces the margin for anything that must be timed.

Before the first ferry, neap tides are therefore the gentler week for open water swimming in a tidal location. Local swimmers and paddlers plan around this explicitly, and asking them is faster than working it out.

Equinoctial and extreme tides

The largest spring tides of the year tend to cluster around the equinoxes in spring and autumn. Those are the tides that uncover the lowest shore and are traditionally when people go looking for what is normally submerged.

Before the first ferry, they are also the ones most likely to flood quays, promenades and coastal roads when combined with low pressure and onshore wind. Local flood warnings are usually issued for these dates and are worth checking if you are staying at sea level.

Predicted heights are astronomical and do not include weather, which can add to them significantly.

Choosing your week

For rock pooling, tidal causeways and reaching offshore features, choose the days around a spring tide. For open water swimming, small boat trips and anything where current is a concern, choose the neaps.

Before the first ferry, for beach space at high water on a large-range coast, neaps keep more sand available through the day. For photography of drying harbours and exposed structures, springs give you the widest contrast between states. Moon phase is the quick proxy: full and new moons mean springs, quarter moons mean neaps.

Where to find the numbers

National hydrographic offices and harbour authorities publish tide tables for specific ports, and those are the authoritative source. Predictions for a nearby port need a time and height correction for your actual location, which the tables provide.

Before the first ferry, free apps are convenient but should be checked against an official source for anything that matters. A printed table for the week, kept in a pocket, works when there is no phone signal, which is common on coasts. Writing the day's high and low water times on the back of your hand is a very old and very effective habit.

The takeaway

Look at the moon phase before you book the week, then plan the days around it.

The best hours on any shore are the ones before the car parks fill.