With high mountains surrounding Slovenia on all sides, the weather is heavily influenced by seasonal and local influences. During the summer, there is usually a moderate NW wind of up to 4 Bf along the coast. Daytime thermals work well here - i.e. A regular strong NW wind (daily breeze or also maestral)
, which blows up around 10 o'clock and stops at sunset. The harbours in the north-eastern Adriatic are characterised by katabatic winds (cold winds that fall from the mountains down into the valleys mostly at night). In stable weather this happens every day between 9pm and 2am and 5am and 7am.
In summer, a jugo (south-easterly wind) or a bora can
also occur. However, it does not last more than 2-3 days. Jugo, unlike the bora, almost never exceeds 7 Bf. Jugo is usually cyclonic in nature, so it is well predictable (signs of an approaching juga: calm seas, light variable winds, gloom on the horizon to the south, increasing temperature and humidity, and gradually decreasing pressure). The winds Lebic (N) and Tramontana (SW, W) are very dangerous and unpredictable. They often occur when temperatures are high in summer and the temperature over the mountains around 1 000 m above sea level is around zero. They bring very bad weather, zero visibility and winds around 45 knots. Thunderstorms also occur in the summer, but they are usually short-lived.
Average summer temperatures are 22-25 °C
. Temperatures can sometimes reach 31 °C. Despite the fact that Slovenia is located in the northern part of the Adriatic, the sea is beautifully warm in summer. The bay is not very deep, so the water in the sea has time to warm up.
In spring and especially in autumn, the wind is very erratic, accompanied by strong storms. The dangerous bora blows here especially in winter. It is associated with stormy weather and can blow for up to a fortnight. It blows from a NE direction (the direction is greatly influenced by the shape of the coastline) and can reach speeds of up to 100 knots. The strongest winds are in the Gulf of Ter. Just as the bora is common in summer, the jugo (strong south to southeast wind) is common in winter, blowing from North Africa. From October to May this wind blows quite frequently, longer and with greater force up to 9 Bf. Because the jugo blows a long distance across the sea, it can raise large 3-4 metre waves. This creates dangerous spots off the northern Italian coast.