THE south will be hit with the highest tide for more than 18 years until the end of the month.

Southampton marine researchers have revealed tides will be at their highest because the Sun and Moon are aligning directly over the Equator.

According to the NOC’s latest research, in some places these extreme tidal conditions can cause sea levels to be 20 inches (50 centimetres) higher than a normal spring tide.

A team from the National Oceanography Centre discovered the change in tide.

Professor Kevin Horsburgh, from the National Oceanography Centre, said: “NOC scientists continue to lead the world in the study of tides and all factors contributing to sea level change. The 18.6-year cycle is a fascinating result of heavenly motions.

“While many features of tides have been known for centuries we are still making new discoveries.”

Tides are controlled by astronomical cycles and every fortnight at new moon or full moon the Earth, Sun and Moon are in a straight line, which creates bigger tidal ranges.

Higher than average tides are called spring tides, but some are higher than others depending on how close the Moon is to the Earth.

NOC researchers say that spring tides are always higher in March and September and the high tides predicted for 2015 are because of a very slow change in the Moon’s orbit.

The Moon’s orbit cuts this surface of the Earth and Sun at an angle of approximately five degrees and over 18.6 years the moon’s orbit slowly rotates around so it cuts through the solar orbit in a different place.

This is called a nodal cycle and has the effect of changing how far above or below the equator the Moon can reach in its orbit.

This year the Moon’s orbit will reach 18 degrees which boosts the chances of the moon being directly overhead at the Equator.

However Professor Horsburgh said it is important to remember that stormy weather had a greater impact, causing storm surges due to low pressure and high winds that raised sea levels by up to 120 inches (3 metres) around the UK coastline.