The formation of cyclones and anticyclones over central and southern Europe dictates changes in Adriatic weather conditions. The usual direction of cyclone movement over the Adriatic is from west to east. Their fronts bring southerly winds (when the jugo blows along the Adriatic), with a flow of warm, wet air to the Adriatic, making the weather cloudy and rainy. Behind the cyclone, as the anticyclone gains in strength and expands over the European mainland towards the east, the wind veers NE and brings with it cold, dry air; the bura clears away the clouds, and following it there is a temporary drop in temperature, but the weather stabilises. This stabilisation is characteristic of Adriatic weather, with clear, sunny skies, and a daily maestral during the summer, until the arrival of a new cyclone repeats the entire cycle.
This rhythm of changes is common in the Adriatic, and varies only according to the frequency and trajectories of cyclones. They are rare during the summer when they mostly move above the Northern Adriatic.
Differences between the north and south Adriatic weather situations are significantly milder during the summer – this is when the two halves of the Adriatic merge into a single climate region, with many warm, sunny days, high daily temperatures soothed by the pleasant maestral, low humidity and nights which are not too hot. The surface temperature of the sea is mostly between 24° and 26°C throughout the Adriatic.
At the end of the summer, the differences between the northern and southern Adriatic become more marked at night, while daily temperatures remain more or less the same. Colder nights soon begin to contribute to the cooling of the sea, which quickly becomes colder around the beginning of September. A month later, the Istrian sea will have cooled to 18°C or less, while in the south it will still be around 22°C.
The amplitudes of the Adriatic tides are relatively small and do not affect safety at sea significantly. Atmospheric pressure has a significant effect on them.
Sea currents are weak and do not usually present navigational problems. But they should still be taken into consideration, especially in narrow channels and passages, where they can gain up to 4 knots in speed.
The waves of the Adriatic are not as high as ocean waves. The jugo creates more waves than the bura, but it would be foolish to conclude that jugo waves are less dangerous. On the contrary, bura waves are half the length, and irregular in amplitude, which means your hull will be under much greater stress than during the jugo.
In terms of weather conditions in the Adriatic, squalls are the most unsettling experiences, next to the bura. They arrive at great speed from the west, from the open sea, but are short-lived. They almost always occur during summer, and lessen in frequency as autumn approaches. At the first sign of a squall, take precautions without delay. If you can shelter from its path, you would be well advised to do so.