January is the coolest month of the year with the average
maximum temperature around 24°C and an average minimum of 14°C. However, records
show that temperatures have been reported as high as 32°C and as low as 8°C during
the month. It is often cloudy and unsettled as mid-latitude weather disturbances
penetrate into the Gulf bringing changeable weather and cool, winter Shamals in
their wake. Such Shamals that sweep down the Gulf frequently produce intense convective
activity resulting in squally, thundery weather with showers, storms and high seas.
On average five or six rain days can be expected during the month, however as many
as seventeen rain days have been recorded. Rainfall is often short lived and intense
with isolated thunderstorms producing the majority of the recorded rain. Large fluctuations
in rainfall occur from year to year with occasional dry years or with as much as
108.8 mm falling during the month. On clear fine days the weather is pleasant and
warm with weak afternoon sea breezes. Sea temperatures are around 21°C.
Temperatures increase a degree or so in February with
mean maximums typically around 25 °C, however the extreme maximum temperature has
reached 36°C with a minimum as low as 7°C. Unsettled wintry weather is more frequent,
winter Shamals persist with the associated unsettled weather and strong winds. This
makes February one of the windiest months with regular Shamals affecting the Gulf.
Shamals bring cool, windy and occasionally showery conditions to the southern Gulf.
Ahead of an approaching shamal strong Southeasterly winds often develop bringing
hot, dry conditions and occasional sandstorms. The transition from Southeasterly
winds ahead of the trough to the Northwesterly Shamal is therefore usually associated
with a marked fall in temperature. February is the wettest month of the year, with
an average of 25mm of rain, it also holds the record for the most rainfall in a
day, 150.2 mm in 1988 at Dubai Airport. The expected number of rain days during
the month is 5 but has been as high as 12. The relatively warm, moist air over the
Gulf combined with winter weather patterns helps to fuel cloud and storm development.
Local convergence and the effect of the mountains in the east of the country also
act to generate or enhance rainfall.
The period March through to May are the "Spring" months
in Dubai when the temperature begins its steady climb towards the summer peaks.
Average maximum temperatures rise to around 28°C in March however winter weather
patterns continue to affect the area. This combination means that a more abundant
supply of energy is available for the development of cloud and storms should the
correct combination of meteorological features exist. March is therefore often a
very changeable month when Dubai can experience a wide range of weather phenomena.
This is why March has the highest expected number of rain days, six on average and
up to eighteen in the past as well as the most frequent occurrence of thunderstorms.
Average rainfall for the month is 21mm but has been as high as 155 mm. As in February,
in between the periods of unsettled weather, winds tend to veer to the Southeast
and bring warm, dry desert air to the coast. Temperatures have been recorded in
the low 40’s °C later in the month however extreme minimum’s of 11°C have also been
As the sun begins to climb in the sky, April brings some beautiful weather to the
Emirates. Maximum temperatures are typically around 33°C, humidity is generally
low and although winter systems are still possible they are becoming a lot less
frequent. Expected rainfall is down to around 7 mm falling on three days during
the month but in exceptional years rainfall has been as high as 60 mm. The coastal,
afternoon sea breeze increases in strength as the temperature gradient between the
land and the sea develops. The increase in temperature does however mean that the
occasional storms that do develop can be violent with heavy rain and squalls. One
particularly violent storm in 1981 produced golf ball sized hail stones and in 2003
a storm and squall produced mean winds of 53 kts gusting to 71 kts. As the month
progresses, the high level Jet stream starts to move northwards, cutting off southward
incursions of unsettled weather and cool Northwesterly winds to the region. The
sea in coastal waters continues to warm up with a mean temperature for the month
of about 25°C.
May often marks the beginning of the summer heat, average maximum temperatures are
between 37 and 38°C, but extremes highs of 47°C have been recorded. The Humidity
is however at its lowest level for the year and rain and thunderstorms are extremely
rare in coastal areas. Hot, dry Southeasterly winds often prevail in May but comfort
levels remain reasonable because of the low humidity. Sea temperatures increase
to around 28 to 29 °C.
During June,low pressure over Southern Iran, which develops in the lee of the mountains,
combines with a ridge of high pressure over Saudi Arabia to produce a Northwesterly
gradient which can persist over the Gulf for up to six weeks. The phenomena is known
locally as the “Forty day Shamal”. From year to year the onset and strength of this
effect can vary widely. Hot and generally dry conditions prevail throughout the
month with periods of Southeasterly winds replacing the Northwesterly flow when
the lee low weakens. When the winds are from the Northwest they bring hot and sometimes
dusty conditions from the deserts of Saudi Arabia, Kuwait and Iraq. Temperatures
typically reach a maximum of around 39°C but can be as high as 47°C, low humidity
at this time helps to keep stress levels reasonably low. Rainfall is infrequent
during June with most coastal stations having a completely dry month. Over the mountains
in the East of the Emirate summer storms do develop and can cause intense localised
heavy rainstorms and flash flooding in the wadi’s . Dry squalls from these storms
do occasionally reach the coast dramatically reducing the visibility for a few hours.
Sea temperatures increase into the low 30’s°C.
As the summer advances and the monsoon spreads northwards over India the lee low
effect over southern Iran begins to weaken and pressure gradients become weak over
the area. Land and sea breezes begin to dominate the flow and as the sea is still
warming up thermal gradients can be strong with a moderate to fresh Northwesterly
sea breeze most afternoons. The humidity can become extremely high at times producing
severe stress. The combination of high temperatures and high humidity can make atmospheric
conditions extremely unstable and summer thunderstorms are not uncommon. As in June
these usually develop over the mountains in the East of the Emirate where the mountains
act as elevated heat sources and where convergence often occurs. Sea breezes on
the east coast force very humid air up the mountains where it combines late in the
afternoon with Gulf coast sea breezes from the Northwest. Inland stations frequently
report Towering Cumulus and Cumulonimbus with thunderstorms, squalls and dust or
sandstorms. Mid and upper level easterly winds then help to propagate the storms
towards the Gulf coast where they can occasionally affect Dubai, Sharjah and the
northern Emirates. Mean maximum temperatures in July are typically around 41°C,Inland
Stations being the hottest with expected maximums of 44°C and all time extremes
around 49°C. Sea temperatures begin to become unpleasantly warm reaching 32-33°C.
Conditions during August are similar to those experienced in July in terms of temperature
and humidity. During the summer as the sea surface temperature rises, the Gulf increasingly
becomes a prolific source of water vapour. Afternoon sea breezes bring this warm,
humid air to coastal areas and can produce some of the years most uncomfortable
conditions. The risk of summer storms persists and although most frequent over the
mountains can occasionally affect coastal areas. Inland desert areas, have a rather
different climate, although summer maximum temperatures in the desert are frequently
higher than those on the coast the mean humidity is up to 20% lower than coastal
areas. This produces rather more comfortable conditions and is the reason that,
prior to the prevalence of air conditioning, many local families would spend the
summer months away from the coast. Mean sea temperatures are around 33°C but have
been recorded as high as 35°C.
As temperatures begin to fall after the height of the summer there is a sting in
the tail for residents of coastal cities. Sea temperatures reach a peak at the end
of August and it is therefore during this time that the potential for warm, humid
air to be advected to the coast reaches a maximum. September is far from being the
most humid month but it has the highest humidity of the hot summer months. For this
reason September is extremely humid and is one of the months with a high occurrence
of fog. Night time temperatures begin to drop into the upper 20’s °C and fog will
often form in the early morning hours. Maximum temperatures can still occasionally
reach extremes of 45°C with extreme minimum’s around 22°C. Sea temperatures begin
to fall later in the month with the mean for the month of around 32°C.
It is the latter part of the year when the weather is the most pleasant and settled
in the UAE. Maximum temperatures in October are around 35°C and although the humidity
remains reasonably high comfort indices have fallen from the extreme levels experienced
in the summer. As night time temperatures continue to fall, faster than the sea
temperature, fog is still a problem in the early morning hours. The weather is usually
dry and settled but there have been exceptional years such as 1997 when several
weather systems penetrated into the area bringing unsettled wet weather and thunderstorms.
The mean sea temperature for the month is 30°C.
Temperatures continue to fall sharply during the month with mean maximums between
30°C and 31°C. As the subtropical jet moves southwards and upper level winds over
the Gulf strengthen there is the increased potential for low pressure systems to
propagate from the North and West into the area. Late in the month it is possible
for the first Shamals to affect the Gulf but it is not usually until December that
unsettled weather reaches the region. Again November 1997 was an exceptional year
with twelve rain days including four thunderstorm days producing 31 mm of rain at
Dubai International Airport. In 2004 a severe line squall and thunderstorm brought
heavy rain (24 mm) and a hail storm that produced stones of up to 1.5 cm in diameter.
By the end of the year winter systems are more frequently affecting the Emirates,
the mean monthly rainfall is 15 mm with rain reported on three or four days during
the month. Mean maximums have fallen to 26°C with minimum’s typically around 16°C.
The humidity is frequently high in the early morning hours with fog still causing
a problem, although Dubai and the Northern Emirates tend to be a little less humid
than other areas of the country. Occasionally persistent periods of unsettled and
wet weather can affect Dubai in December. Rainfall totals have been as high as 130
mm with a 24 hour maximum rainfall of 73 mm. Sea temperatures fall to around 23°C.