The Nadur Weather
Observatory is located on the island of Gozo, situated at 36°
02' 26''N and 14° 17' 35''E, forming part of Malta, an independent
state located approximately 90km south of Sicily in the centre
of the Mediterranean Sea. The Maltese Islands have a typical Mediterranean
climate with relatively mild, wet winters, and hot, extremely
The 'winter' season usually commences
between mid-September and early October, when the first heavy
rains affect the islands. Depressions start making their way into
the Mediterranean at this time of year, driven by the apparent
southward movement of the overhead sun from the Equator to the
Tropic of Cancer. This movement causes the three Hadley cells
in the northern hemisphere to 'elongate' southwards. The descending
limb of the Hadley cell nearest to the Equator which during the
summer months gives an almost permanent high pressure over the
Central Mediterranean region is replaced by the rising limb of
the second Hadley cell (also known as the Ferrel Cell), which
causes low pressures (depressions) to form over relatively low
latitudes (30 - 50°N) over the Atlantic Ocean. These, then,
travel eastwards to affect mainland Europe.
Some of them take a southeastwards trajectory
and enter the Western Mediterranean, where they usually intensify
due to the relatively warm sea temperatures which are maintained
even during the winter months. Some depressions enter the Mediterranean
from the Gulf of Lions and intensify over the Gulf of Genoa. Others
form over the Sahara Desert and enter the Mediterranean from the
southwest. All these affect the weather over the Maltese Islands
by bringing rain, gales and sometimes severe weather, including
severe gales, flooding rain, hail and thunderstorms.
Temperatures have never fallen below the freezing
point in the Maltese Islands, at least since records started being
taken in these islands approximately a century ago. However, in
extreme cases, the period from December to February can contain
very cold days (at least to the people of these islands!) with
maximum daily air temperature sometimes reaching only 6 - 8°C
and nighttime minimum temperature falling as low as 1 - 3°C.
These cold snaps, when accompanied by high winds, drive the wind-chill
temperatures down to well below freezing.
This state of affairs remains so until the
middle to the latter part of March, when the overhead sun starts
to make its run from the Equator to the Tropic of Cancer (23.5°N).
The Hadley Cells start to 'contract' again, thus dragging with
them the depressions to the northern latitudes. In fact one can
say that the rainy season in the Maltese Islands ends by the end
of March. April and May are characterised by changeable, but mostly
fine weather conditions, with the occasional gale, thunderstorm
and some rainfall. The hot, dry, summer season starts in
earnest between late May and the middle of June, with cloudless
skies, light winds and an almost total drought. It is not uncommon
for the Maltese Islands to have no rain recorded whatsoever for
over 100 days between the middle of May until late September or
the middle of October. However, June still can have the solitary
gale and shower at times.
Heatwaves are quite common during this
season. Temperatures of over 35°C are considered as the norm
especially during July and August. During the 1990s, temperatures
of over 40°C have occurred almost annually. Humidity is quite
high during the summer months, especially when the wind blows
from the southern quadrants. High temperatures combined with high
humidity make life unbearable in the Maltese Islands for those
without any air-conditioning.
As stated above, the summer season then ends,
usually abruptly with the first heavy thunderstorm, around the
middle of September, although maximum air temperatures remain
quite warm (22 - 26°C) until very late in October, and sometimes
up until late November.
The prevailing wind in the Maltese
Islands is the Northwesterly wind, known locally as the Majjistral.
It blows for about a third of the year over these islands. During
the hot summer months, winds are usually light and variable and
a sea-breeze sets in from mid-morning to late afternoon.
Sea temperatures are quite mild all
year round, with the lowest point reached in January and February
(15°C) and the highest between late July and the middle of
Visibility is generally good
all year round, especially in May and October, where excellent
visibility is common. In fact on certain days during these months.
Mount Etna, which lies about 200km to the NNE can be seen.