The climate at the Adriatic is typically a Mediterranean one, with mild rainy winters, and hot and dry summers. The air temperature changes depending on the area.Sailors must however be careful as the weather can change very quickly.
Summer temperatures in July will be about 34°C in the northern part, while in the southern part they will rise even to 38°C. In the winter, the coldest temperatures are noticed in the northern Adriatic (up to -10°C), while they will not have exceeded 6 °C in the southern part.
At the Adriatic Sea, the bora, sirocco and north-western wind blow most often.
Bora (Cro.: bura) is a dry, cold downward wind blowing in bursts from the north-northeast to the east-northeast direction. The direction in which the wind blows is mostly influenced by the configuration of the shore. The strength of bora is explained by the existence of warm air over the surface of the sea, and a cold layer of air above mountain ranges in the littoral, which cause a strong streaming due to equating of the pressure. Cold air tends to fill the void which occurs due to the rising of the warm (lighter) air from the sea surface. Bora blows mostly in the winter. In the summer, it usually lasts for a day or several hours, while, in the winter, it can blow as long as 14 days.
Sirocco (Cro.: jugo, siroko or silok) is a warm and moist wind which blows from the direction east-southeast to south-southwest. Its consequences are high waves and rain. Sirocco is a characteristic wind for the southern Adriatic, where it blows longer and stronger than in the northern part. In the summer, it usually blows as long as 3 days, and in the winter even as long as 3 weeks. The signs of the oncoming sirocco are the calm at the sea, weak changeable winds, dimness of the horizon, the increase of the temperature and moisture, and the gradual decrease of the pressure. Waves from the direction of the southeast become bigger.
The landward breeze (Cro.: maestral, maestral, smorac) is a daily, thermic wind blowing from the direction of the northwest, and it occurs as the consequence of the difference in the speed of warming up of the land and the sea. It is present from the spring to the autumn, and, during the day, it often changes the direction of blowing. The landward breeze is more present in the southern Adriatic than in the northern Adriatic, and it starts to blow earlier there.
The stiff breeze (Cro.: burin) is a wind blowing contrary to the landward breeze. It blows during the night from the direction of the north, north-east in the northern Adriatic, and in the southern Adriatic, from the east or south-east. It is the strongest before the dawn, and after that it stops soon.
Data About Weather
Weather forecasts are made by the State Hydrometeorological Institute, and they can be heard on VHF frequencies of coastal radio stations and harbor master’s offices. They are also broadcast on FM stations or at the end of the news or within broadcasts for seamen. Harbor master’s offices constantly send weather reports and warnings on their VHF operating channels, in four languages. It is possible to get forecasts with the presentation of the synoptical situation in all the marinas and harbor offices.Or web http://meteo.hr/index_en.php
Nautical Radio Service and Communications Service
The whole of the Croatian coast is covered by radio communications rather well. The radio service for protection of human lives and safety of navigation is provided by Plovput from Split, through radio stations Split and Dubrovnik, which cover the southern Adriatic, and Rijeka, which covers the northern part of our sea.
According to the standards of the GMDSS system (Global Maritime Distress and Safety System), the channel for automated receipt of digitalized distress calls is the channel 70, after which the communication is transferred to the operating channel of the coastal station, i.e. a harbor master’s office (16 or 10). GMDSS system has been in use since 1 st February 1999, and on the present VHF channel for distress calls, the channel 16, constant listening will be possible still for some more time.
HOW TO PREDICT WEATHER ON ADRIATIC
Indication of bad weather
-low atmospheric pressure
-sudden decrease of NW wind
-moon of pale colour with the dissolving ring around
-red sky or rainbow in the daybreak
-strong wind in at the clear sky daybreak
-sudden change of Bura direction to E
-grey clouds accumulating on the western horizon
-dissolving ring around sun or the moon, during high humidity wind
-constant low atmospheric pressure during bad weather – weather will not change for longer period
Indication of good weather
-increase of atmospheric pressure (above 1012hPa)
-bright sky on western horizon during bad weather
-common condition – wind after rain brings good weather
-red colour after sunset on the cloudy sky
Indications that the good weather will continue
-NW wind during day and N at the daybreak or in night
-extreme low tide, or regular change between the tides
-red sky after the sunset
-stable high atmospheric pressure or rising
-bright sky without wind
-while strong Bura is blowing no rainy weather should be anticipated.
Adriatic coast in summer the time usually works Azores High, which typically brings high air temperatures. In winter the contrary, when the weather begins to operate a branch of the Siberian anticyclone, and it is with this anticyclone bind the lowest air temperature of the Adriatic measures during the year. But one thing is certain; anticyclone associated with the stable, and a cyclone with an unstable time! In the vertical section of the two systems can be clearly observed lowering of air in anticyclones and lifting the cyclones. The rules of physics are simple in this regard; air that descends always heats and dries out (so anticyclone associated with stable weather), and the air is cooled when lifting, the water vapor in it condenses (because cyclones bring clouds and precipitation).
In the Eastern Mediterranean, the tidal range is very small: 30 cm to 60 cm (one to two feet depending on location) including the variation of level due to atmospheric pressure and dominant winds.
When you arrive at the marina,port, reception provide you with a weather forecast for the next 24 hours. Harbour Offices receive a weather forecast regularly; this is the best and most reliable source of weather information. On your VHF watch channels you can follow the transmitting time of meteorological reports, and navigation warnings. This information is broadcast by mainland radio station.
Channels ………….. 73
Times …………… 05.45; 12.45; 19.45
Channels ………….. 4, 7, 85
Times …………… 06.25; 13.20; 21.20
Weather forecasts are in Croatian and English. In high season it is in Italian. If you cannot obtain a weather forecast, you can contact The Moorings Customer Service.
Also check my page https://cro-sail.xyz/weather
Best Seasons for Sailing in Croatia
The best sailing season is late spring ( April through June) and early fall ( September through October). The sea is calm, the weather mild and there are fewer crowds. July and August are ideal months for swimming plus the summer social season is in full swing. Reserve in advance though!