Introduction

Due to the location of Kuwait in the Sahara geographical region, the weather of the country is characterised by long, hot and dry summers and short, warm and sometimes rainy winters. Dust storms almost always occur with a rise in humidity during summer.

The highest temperature ever recorded was 52oC in July 1978, (making Kuwait the fourth hottest place in the world). The lowest temperature, -6oC, was recorded in January 1964. There is a wide variation of temperature, ranging from an average of 45oC in summer to an average of 8oC in winter. Such climate fluctuation is often accompanied by a change in the annual rainfall -- which may vary from 22 mm one year to 352 mm the next.

CLIMATE PATTERNS

Desert climates such as those prevailing in the Arabian Gulf region tend not to have sequences of organized weather patterns. The area is moist in summer but has most rainfall during cold periods and precipitation amounts decrease from north to south, with a large range of air temperatures (of about 24 degrees).

Winds

The low tropospheric levels over the Arabian Gulf experience a strong but shallow northwesterly wind flow (>60 knots) during colder air penetration. In middle and upper troposphere levels, the wind flow is dependent on the strength of the subtropical jet stream. The relationship between the surface and upper-level pressure patterns determines the surface wind duration. Short shamals (Arabic word denoting winds from the north) are associated with a fast moving upper-level trough that travels in 12-24 hours from the northern to southern Arabian Gulf. Longer shamals (of three to five day duration) persist as long as the upper-level trough remains over the Gulf of Oman.

Usually, high pressure ridges advance into central Saudi Arabia with decreasing surface pressure over the Gulf of Oman. Increases in surface pressure are primarily related to the African high as it penetrates into Arabia. A decrease in surface pressure over the Arabian Gulf is primarily related to the Indian monsoon low. The two pressure systems are the key factors in controlling surface winds over Arabia. For example, shamals are strongest on the Arabian side of the Gulf and fade away gradually towards the Iranian coast. The shamal weakens at night while remaining strong aloft, and sea breezes prevail over the Arabian Gulf in the absence of a shamal. Weather conditions associated with each shamal onset vary.

The air temperature over the Arabian Gulf decreases following northwesterly winds. A summer shamal is dry, with potential to produce dust and sand storms. High cirrus clouds frequently appear over the area in association with the penetration of the Indian monsoon low. Kaus winds (surface winds primarily from a south to south-east direction) are considered to be a pre-shamal situation. There are two kinds of distinguishable kaus winds. One prevails over the entire Arabian Gulf and the other persists up to the central Arabian Gulf..These occur from September through early May. Both transport dust from the open plains of central Saudi Arabia into the Arabian Gulf, and are generated ahead of a south-easterly moving frontal system during winter. Kaus wind durations range from 20 to 48 hours and frequently reach 30 knots.
Spring and summer kaus prevail up to the central Arabian Gulf (about 28°N). These kaus are very short-lived phenomena characterized by warm and moist air. The exact duration of these winds is related to regional circulation such as the Sudan low, African high-pressure and Asian high pressure systems.