Despite the name, spring tides occur throughout the year when the Moon is either new or full and when the Sun, Moon, and Earth are aligned and there is the greatest difference between high and low tide.

In Spanish they’re known as mareas vivas and occur here more frequently in September and March.

But on this occasion other factors have been added into the mix that will make these tides exceptionally high, even up to half a metre more than in previous years. And the same will happen with low tide, which will be abnormally low.

These factors include if the moon is closer than usual to the Earth or if it is above the Earth’s equator.

The climax of these conditions will be reached this Wednesday September 18th, coinciding with the full Moon, but the main impact of this won’t be felt until Thursday.

The phenomena is expected last at least until Friday and will rise the tides on practically the entire northern coast, with waves in some areas reaching a height of five metres.

The Marine and Food Research Center of the Basque Country (AZTI) has reported that this week, between this Tuesday and Friday, “exceptionally high” spring tides will be recorded in the Bay of Biscay, which will coincide, depending on the days, between 5 and 8pm.

The Basque towns of Zarautz, Pasaia and Irun have been put on yellow alert and could even experience waves close to five metres.

In Galicia, in the next couple of days, they could even experience the highest spring tides in the past 19 years.

The maximum predicted record will be reached in the Foz estuary in Galicia on Thursday September 19th around 6pm, when the high tide will reach a height of 4.6 metres.

In Ferrol and A Coruña, other strategic points on the Galician coast, it will be 4.4 metres, while in the estuaries of the Costa da Morte it will reach 4.3 metres, and in those of Vigo and Pontevedra waves will be an estimated at 4.2 metres.

Regions along the Cantabrian Sea such as Cantabria and Asturias will also be affected with bigger waves and higher tides than normal. While reports haven’t indicated predictions as high as the waves in Galicia and the Basque Country, people there still need to be on the lookout for high tides in the late afternoon and evening of Thursday.