Weather on Adriatic
Sea, temperature and seasons
Winds of the Adriatic
Forecasts and weather info
Introduction
The fact that the north Adriatic almost touches
the Alps causes certain climatic differences between
the north and the south Adriatic coast. They are
not so visible during the summer, but in the winter
the weather pictures of the north and the south
are often very different. The borders between
the two faces of the same sea are very clear -
it's cape Ploca, known between the sailors as
Punta Planka, two miles south from Rogoznica,
on the rout to Šibenik on the way to Split.
Cyclones and Anticyclones
Weather changes on the Adriatic dictates the changes
of cyclones and anticyclones over the middle and
South Europe. The usual travelling way of cyclones
over the Adriatic is from west to east. On their
front side they bring winds from the south with
warm and moist air, so the weather is cloudy and
rainy. Behind the cyclone with the growing of
anticyclone and it's spreading over the European
land through the east, the wind moves to the north-east
and brings cold and dry air, north-eastern wind
chases the clouds, which stabilizes the weather.
Until the arrival of the new cyclone the weather
stays sunny and calm, with a daily landward breeze
during the summer.
This rhythm of change is usual for the Adriatic,
and it differs only by how often and from where
do the cyclones come. In the summer they are rear
and they travel mostly north of Adriatic, in the
winter they are more powerful and dipper. They
travel one after the other from the Geneva Bay
and Triennia Sea, through south Italy over to
south Adriatic and further to the southeast.
The differences between summer and winter
In the Summer the differences between the north
and south are much smaller- both sides of the
Adriatic are combined into one climate territory
with a lot of warm and sunny days, high daily
temperatures which get softened by a pleasant
landward breeze, low percentage of humidity and
not to hot nights. The temperature of the sea
surface is between 24°C and 26°C on the
entire Adriatic.
At the end of the summer the differences between
the north and the south Adriatic become more noticeable
during the nights, while the daily temperatures
are pretty much the same. Colder nights soon lead
to differences in the sea temperatures. In the
beginning of September the sea starts to get colder.
On the north the sea temperature falls to 18°C
and more, but on the South it can still be 22°C.
The air temperature during the winter is different
as well. In the Trieste Bay and under the Velebit
the snow carried by a strong storm is not so rear,
while at the same time on Hvar, Vis and Korèula
the weather can be very pleasant. Especially during
the winter, cape Ploca proves to be worthy of
its name - the climate border - very often two
types of weather are fighting over it.
Temperatures
The warmest months are July and August when the
air temperature is between 25° C and 35°
C (77° F - 95° F) and the sea temperature
reaches up to 28° C (83° F). The rain
is very rare. This is the time when most of the
tourists come.
If you're for a quieter time at the beach and
not so many tourists, maybe June and September
are months for you. They are also very warm months
with average temperatures around 25° C (77°
F) and the sea surface temps between 20° C
and 25° C (68° F - 77° F).
Sunbathing and swimming is also possible in April,
May and October, but it really depends on the
weather and chances are that you'll get more sunshine
in the southern Adriatic. In that period expect
temperature between 15° C and 25° C (
59° F - 77° F) and the sea temperature
between 16 and 21° C (61 - 70° F). This
is a period with more rain and windy days.
The air temperature in winter months is between
5 and 10° C (41-50° F) and the sea temperature
are in average 12 ° C (54 ° C).
Sea changes, current and waves
The changes of high and low tide in the Adriatic
are small and don't effect the safety of the sail.
On the south the difference between the tides
is rarely higher then 40cm, but as you approach
the North the amplitudes will become bigger -
around Istra and Trieste Bay the middle extreme
amplitude is almost 1m. During the long lasting
and strong south winds in some narrow canals and
bays the tide can grow so big that it can flood
over walls on the beaches in harbours. This is
very rear (more often in the winter), and it's
characteristic for the big and deep bays of the
south Adriatic. During south winds the tides are
usually higher, and during storms the sea is lower
than the average. The atmosphere pressure has
a big impact on them as well.
Sea currents are small, and present no problem
during the navigation. But you still have to keep
them in mind, especially in some narrow canals,
where they can get up to 4 knots of speed.
The waves in the Adriatic are not as high as the
ones in the oceans, but that does not mean that
they can't be unpleasant for smaller boats. The
south wind creates bigger waves then northeastern
wind (the biggest measured south wind wave was
10,8m, and the north-eastern 7,2m), but still
it would be wrong to presume how the south wind
waves are more dangerous because they are bigger.
On the contrary, northeastern wind waves are shorter
by half, but still shaped unsymmetrical, which
means that the boat will suffer more in the waves
of the northeastern wind. The landward wind waves
get pretty high on the South, it can get up to
4m of height.
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The entire east side of the Adriatic has it's
own weather changes, especially the winds. Since
the old days fisherman could read the small signs
of nature and know what the sky is preparing next.
That's why you cant make a mistake by asking a
fisherman what's the weather going to be like
in the evening or the next day and where is the
best place to anchor for the night.
North-eastern wind
As a cold wind, the north-eastern (in Croatia
called ''bura'') is blowing from the continent,
from the eastern side of the Adriatic towards
the open sea and brings bright weather. It starts
abruptly and blows in squalls toward the sea.
It is strongest in the Velebit Channel and the
Gulf of Trieste. In the summer blows as a local
wind and then lasts only a few days. In the winter
it may continue for six to fourteen days.
For smaller boats it can be very unpleasant. Without
it the Adriatic, especially the north part, would
be much more pleasant Rarely it blows more than
3 days. When it's local it can start and stop
within 24 hours, but if it's wide and continental
it can last the entire week, and in that period
it gets weaker or stronger a couple of times.
Sudden starting of the wind is one of its most
dangerous sides, especially for less experienced
sailors. At the coast it can easily reach 40 -
50 knots, during the winter even more. As it brings
cold and heavy air, it finds it's way towards
the sea through the mountains. That's why it's
best to hide from it in the bays underneath the
mountains.
The South wind
It is the warm wind from the southeast (in Croatia
called "jugo" or "sirocco")
it blows through the Adriatic, during the cyclone
it brings clouds and rain. The air pressure falls.
It develops slowly; usually you can notice it
two or three days before. As it blows through
the canal, it produces high, but long waves. It
usually lasts much longer than the north-eastern
wind, five to seven days. In the summer it may
appear as a local wind and is more frequent in
the southern part of the Adriatic. Between March
and June it blows in the north as well. During
the winter even longer. There are also, so-called
dry south winds, they last longer, do not bring
rain, but can be powerful as a storm.
Other winds
The north - western wind (in Croatia called "Maestral")
is a local wind, which blows from the sea, mostly
in the summer. It usually starts between 10 and
11 in the morning and reaches its greatest strength
between 2 and 3 in the afternoon to die down at
sunset. It brings good weather. It is usually
accompanied by white clouds.
The north-easterly wind (in Croatia called ''Burin'')
blows in the summer from the mainland.
The northerly wind (in Croatia called ''Tramontana'')
is a type of bora.
Another type of bora is the easterly wind ''Levante''.
From west blows ''Pulenat'' and from south-west
''Lebic''.
The landward breeze
That's a good wind, friendly to sailors, and pretty
much to every one who enjoys the summer sea because
it softens the heat. It's a daily thermal northeast
wind. It's very usual from spring to fall, and
the strongest in July and August.
It usually starts around 9 or 10 in the morning.
It gets the most powerful in the afternoon, and
it ends with sunset.
It's usually weaker on the north Adriatic than
on the south, where in the canals between islands
it's force can get unpleasant for small boats.
Sudden storm (called "Nevere")
Next to the north-eastern the sudden storm on
the Adriatic is possibly the most unpleasant experience,
especially for small boats. They are thermal storms
that come speeding from the west, from the open
sea; they last short but have great force. They
are the most often in the summer, and they get
very powerful as fall comes.
On the smallest sign of the storm you should,
with no delay, take every precaution, because
the time is short. If there is any possibility
of getting away from it's way, you should. Before
the storm starts it's totally quiet, and often
in the last minutes before it breaks a breeze
blows, very shortly towards the storm - it makes
it impossible to hear the sounds of thunder, that's
why a lot of people where caught by the storm
totally unready.
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Forecasts giving the present state and likely
development of the weather are given in regular
bulletins or by radiotelephone.
Radio forecasts. These begin with a description
of the weather (i.e. wind 7 Bf freshening, sea
5 increasing, fog etc.); this is followed by the
general situation and forecast for the next 12
and 24 hours in the Adriatic and Otranto. Coastal
radio-stations RIJEKA RADIO, SPLIT RADIO, DUBROVNIK
RADIO give forecasts three times a day in the
national language followed by English. Other important
radio-stations are MALTA RADIO, TRIESTE RADIO
and the Italian RAI service.
Special warnings are transmitted as soon as storms
or other weather conditions are expected and these
are repeated following the next period of radio
silence.
The present situation and forecast can be provided
for smaller sections (sectors/quadrants) given
by name on separate map (index map).
The Croatian naval meteorological service divides
the Adriatic into northern, central and southern.
Weather (meteorological) bulletins provide weather
charts with meteorological tables for places on
the Croatian coast, details of synoptic situation,
weather forecasts. They may be obtained from harbour
master's offices or by NAVTEX (radio-telefax).
Maritime Meteorological Centre in Split provides
weather information over the telephone and radiotelephone.
Weather reports
Weather reports are broadcast on these channels
at the following times (UTC):
Rijeka Radio VHF (channel 24): 0535, 1435 and
1935
Split Radio VHF (channels 07, 21, 23, 28): 0545,
1245 and 1945
Dubrovnik Radio VHF (channels 04, 07): 0625, 1320
and 2120
Weather online
Croatian Meteorological and Hydrological Service
Croatian Nautical forecast (Aladin.hr)
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