NOAA’s CLIMATE SUMMARIES FOR THE MIDDLE EAST AND IRAQ
April 7, 2003 — Geologists say that millions of years ago the Middle East had a mild, humid climate, with large areas covered by a shallow continental sea. When the single-celled planktonic plants and animals living in that sea died, they sank to the bottom and were covered by soil sediments and other plankton. Over time, they decayed into oil — an important fossil fuel that is this region’s most valuable natural resource. Today, much of this region is part of the large subtropical desert that extends across North Africa and southern Asia.
Weather data for Iraq and surrounding countries have been collected over the years by the Federal Climate Complex, which includes the NOAA National Climatic Data Center, the U.S. Air Force and the U.S. Navy, collocated in Asheville, N.C. These data allow the public (and war planners) to get some perspective on the weather conditions that troops and their commanders are likely to encounter as they confront Iraqi forces in the Arabian Desert.
Meteorological records for Kuwait and Bahrain go back to the 19th century (when they were British protectorates) and for Jordan and Iraq from after World War I (when they became League of Nations Trust Territories). Unfortunately, however, records of ground observations in Iraq have been limited since the Iran-Iraq war in the 1980s. The military is using its own meteorologists to monitor weather conditions in the area now (as it did in the 1991 Gulf War), but once the military campaign ends, NOAA researchers will use the same data to help with the humanitarian efforts, according to Thomas Karl, the NCDC director.
In general, the climate of Iraq is similar to that of West Texas — hot and dry in the summers, and cool and a bit rainier in the winters. In most of the country, daytime high temperatures average above 100 degrees F during the summer and often remain above 80 degrees F at night. In the winter, nighttime temperatures dip into the 30s and 40s, and only rarely drop below freezing; although in mountainous regions they are correspondingly cooler.
July average monthly temperatures range from the 90s along the Iraqi-Saudi Arabia border to more than 100 degrees F in Kuwait City. Even in the higher elevations of the Arabian desert, July averages in the upper 80s. The average daily high in July ranges from about 99 degrees F to 113 degrees F with average daily lows in the upper 70s to mid-80s. The highest temperatures recorded range from the 110s to 120s, with Dhahran, Saudi Arabia, claiming an all time high of 124 degrees F. In places like Riyadh, Saudi Arabia; Baghdad, Iraq; and Kuwait City, Kuwait, virtually every day from May through September has a high temperature greater than 90 degrees F. Riyadh, Saudi Arabia and Kuwait City, have, on average, more than 200 days per year with daily highs greater than 90 degrees F — more than half the year. The intense heat is accompanied by incredibly dry air. Afternoon relative humidities in July average anywhere from 5 percent to 15 percent.
Fortunately, winter months are more tolerable. Daily highs in February average in the 60s and 70s with daily lows mostly in the 40s, although freezing temperatures have occurred in most places. Extreme high February temperatures range from 84 degrees F in Baghdad, Iraq, and Badanah, Saudi Arabia, in the north, to 96 degrees F at Dhahran, Saudi Arabia, in the south. Wintertime temperatures are generally lower at higher altitudes and more northerly locations. For example, the lowest temperature recorded at Hail, Saudi Arabia, (which is more than 3,000 feet high) from 1973-1993 was 16 degrees F, while the lowest temperature at Dhahran, Saudi Arabia, (a southern station along the Persian Gulf coast) was only 36 degrees F. Only the northern mountainous regions along the Iranian and Turkish borders experience cold winters with occasionally heavy snows that melt in early spring, sometimes causing extensive flooding in central and southern Iraq.
Dew points and humidities are usually quite low, except at times in areas closer to the Persian Gulf where moisture content of the air is greater and summer heat indices can exceed 120 degrees F.
Rainfall is even scarcer to the south with average annual precipitation of 1.5 inches at Badanah in the northern interior of Saudi Arabia. Precipitation here, like most deserts, varies considerably from month to month and year to year. For example, Riyadh, Saudi Arabia, had 5.2 inches of rain during its wettest ever month, which is well over the annual average of 3.8 inches. Desert rains also frequently occur in torrential downpours. The greatest 24-hour rainfall at Hail, Saudi Arabia was 2.5 inches, which is nearly equal to the annual average of 2.6 inches. On the other hand, months often go by with no rainfall at all.
In general, roughly 90 percent of the annual rainfall occurs between November and April, while the remaining six months (particularly the hottest ones of June, July and August) are dry. Rainfall from February through April averages from about 0.6 inches at Badanah to 2.4 inches at Baghdad — roughly one-third to one-half their respective annual normal rainfall.
Thunderstorms sometimes accompany the rain, particularly in the spring when, on average, the eastern reaches of the region see 14 days with thunderstorms each year, while in the west, thunderstorms occur only a third as often. And when thunderstorms do occur, they are frequently evening events.
During winter and early spring, low visibility is common at night and in the early morning in the Tigris and Euphrates river valleys when fog and stratus clouds prevail. This is intensified by strong thermal highs over Iran and in advance of low-pressure systems out of the Mediterranean. Fortunately, fog and stratus clouds occur mostly at night and towards sunrise and burn off before midday (in most cases).
There are two common storm tracks in the area. In the first, storms move through the Mediterranean just south of Turkey and curve northward into the Caspian Sea. Multiple cloud layers (low cloud to cirrus clouds) and precipitation with the low can take from two to four days to transit Iraq. Mediterranean storms that follow the second storm track come out of the sea into Jordan, Syria and Iraq on the way into the Persian Gulf. They exit the area through the Strait of Hormuz and the Gulf of Oman into the Indian Ocean and eventually move toward India. These systems also cause multiple layers of cloud cover one to two days ahead of and one to two days behind the system. Most storms pass through in two to three days, but some stall and take as many as six days to move out of the area. The second cause for cloud cover is the subtropical jet stream, which flows across the Arabian Peninsula and brings a band of cirrus clouds through the area. Deep low-pressure systems displace the jet south for short periods.
Another unique climate feature in Iraq are winds. Specifically, the summer months are marked by two kinds of wind phenomena: