The UAE has a sub-tropical, arid climate. Rainfall is infrequent and irregular. Falling mainly in winter, it amounts to some 13 centimetres a year. Temperatures range from a low of about 10 degrees celsius to a high of 48 degrees celsius. The mean daily maximum is 24 degrees in January rising to 41 degrees in July.

Situated between 22 and 26 degrees north, the United Arab Emirates lies within a sub-region of the northern desert belt, characterised by scanty and erratic rainfall, and high levels for temperature, humidity, and sunshine. Winter sunshine averages eight hours per day, while the summer figure reaches as high as eleven hours a day. Despite this apparently stable climatic picture, the weather does show a remarkable degree of local variability, throwing up thunder storms, fog, gale force winds, sand storms and, of course, rain. Average precipitation figures count for relatively little here since the range of readings , from one year to the next often exceeds twice the nominal ''average'' figure , i.e. roughly 8 cm (80 mm) per year. Most rain falls in the winter months, from November to April. Less frequent, but nevertheless important rainfall occurs in isolated summer showers, carried into the area by south-westerly monsoons, and often occurring at the eastern edge of the great Rub al Khali, along the borders between Abu Dhabi and Saudi Arabia.

Weather Chart
The weather chart during much of the year shows a ridge of high pressure extending southwards into central Saudi Arabia with lower pressure over the eastern Gulf. Prevailing light to moderate north-westerly winds, known by their Arabic name shamal, meaning 'north', are associated with mid-latitude disturbances. Along the western coastal plain, sea breezes tend to dominate with light south-south-easterlies at night being replaced by moderate north-westerlies during daytime. This pattern changes on the east coast where the proximity of the mountains results in gusty and less predictable wind shifts. A good strong blast of northerly shamal is usually preceded in the UAE by strong southerly winds, raising desert sands and reducing visibility. The shift to northerly winds may be quite sudden and can be accompanied by rain, thunder storms, or dust-storms. At sea, conditions can become quite difficult for small boats with force seven winds whipping up twelve foot high waves. In summer, weather charts usually indicate a broad area of low pressure, extending from the western Sahara, across the Arabian peninsula and across Asia, to China. Local pressure variations in the Gulf combine with this to create weather conditions in the UAE. Steady north-westerlies, predominating in the central and northern regions of the Gulf, do not generally extend as far south as the UAE. When they do so, sea conditions around Abu Dhabi become quite rough, while the rest of UAE's coastal waters experience only slight swells.

The UAE is the first country in the Middle East to introduce the Satellite Delivered Information System technology (SADIS), a weather forecasting technology which covers the globe, with the exception of Polar Zones. According to the National Meteorological Authority (NMA), which is affiliated to the Ministry of Communications, the system supplies data on temperature, humidity, volcanoes and wind directions. It also enables the UAE to receive the latest forecasts for centers all over the world through direct contact with the world center in London. The NMA has qualified forecasters to operate the system, and is currently training more forecasters to operate it.

Arabic interest in the weather and in the different types of winds blowing across the desert stems from the Bedouin tribes, for whom changes in weather could mean the difference between life and death. For them, each wind had its own characteristics and was known by a different name; thus, the main period of storms was Al-Barih al-owd, while the minor storm period was called Al-Barih al-sagheer. The first major Shamal occurring around May 25th is the Al-Haffar, or the driller since it drills huge depressions in the desert dunes. The second, arriving in early June, coincides with the dawn star, Thorayya (Pleiades) and is therefore named Barih Thorayya. During this one, which is somewhat more violent than the others, fishermen tend to remain in port, not just because of the wind's strength, but because ancient folklore tells them that this wind devours ships! Near the end of June, the last shamal arrives, known as the Al-Dabaran. It is a violent wind, continuing for several days. Local residents keep doors and windows firmly barred in a battle against the all-penetrating fine dust driven by these shamal winds into every conceivable nook and cranny.

The summer months, from June to September, are too hot for comfort. Midday temperatures range from 35C to 42C, and occasionally top 49C at the height of summer. During this period there is a sharp drop in night time temperatures, with these falling to roughly half the midday readings, i.e. 20C to 28C, and providing a welcome respite from the searing heat of the day. Gulf waters exert a modifying influence on coastal zones, which experience less dramatic diurnal fluctuations in temperature, and higher humidities than inland regions. Although the evenings are not so cool, coastal towns do have the advantage of pleasantly refreshing sea-breezes . Mountainous regions are also cooler and less humid. From December to March, the climate is considerably more equable with midday temperatures ranging from 25 to 35C and falling to as low as 9C at night.

Monthly Temperature (C )

Temp. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Mean Max. 24.2 25.0 29.0 34.0 39.0 41.1 41.8 41.1 39.6 35.8 30.9 26.0 34.0
Mean 18.3 19.2 22.5 27.0 31.3 33.6 35.1 34.6 32.3 28.6 23.8 20.0 27.2
Mean Min 12.4 13.3 16.1 19.5 23.3 25.8 28.1 28.3 25.4 21.6 17.2 14.1 20.4

Mean Monthly Relative Humidity (%)

Humidity Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Mean Max 89% 98% 86% 80% 76% 82% 82% 83% 86% 86% 87% 89% 85%
Mean 63% 62% 57% 50% 46% 51% 54% 56% 56% 55% 59% 64% 56%
Mean Min 36% 34% 27% 20% 17% 19% 25% 29% 24% 23% 29% 37% 27%

Monthly Rainfall (mm)

Rainfall Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Mean 14.4 37.9 26.2 09.4 01.9 00.3 01.3 02.7 01.0 01.5 02.7 11.4 110.7

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