Desert Winter Turns Troops’ Sweat to Shivers : Saudi Arabia: After the swelter of summer, chilly nights and biting wind have taken forces by surprise. And the harshest weather is yet to come.

Marine Cpl. Roger Gance had left his sleeping bag in the rear.

Given the searing heat and scorching sand that Gance had endured over the last three months, it seemed to him that it would hardly matter. But last weekend, the California man lay shivering on a barren hilltop, wishing he had more than a space blanket--a lightweight, super-efficient insulating cloth--to fend off the cold.

Winter has come to the desert, bringing winds howling from the north and sending the mercury plummeting after dark. For American troops constantly exposed to the elements, the sudden change means a new way of life.

“Believe it or not, kids have started writing home saying: ‘Send me my polypropylene long-johns,’ ” said Lt. Col. Charles Kersaw, commander of the Camp Pendleton-based 1st Reconnaissance Battalion.

Marines who only a month ago drank gallons of liquid to avoid fainting in the 130-degree temperatures now pore through catalogues from Eddie Bauer and Brigade Quartermaster in search of down-filled jackets and Gore-Tex gloves.

They don field jackets or ponchos and even woolen hats at sundown, when temperatures begin plunging, sometimes 40 degrees or more from the noontime high. Daytime temperatures rarely exceed the mid-80s and drop well into the 40s at night.

After months of preoccupation with the constant heat and its effects on men and materiel, commanders are having to cope not only with drastically different temperatures but also with periodic gale-force winds that kick up sand and sea and can incapacitate military operations.

In the clearest example to date, the military here on Monday announced again the cancellation of plans for a dramatic amphibious assault exercise south of Kuwait after a second straight day of high seas prevented Hovercraft landing vessels from making their way ashore.

A Navy spokesman, Cmdr. J. D. Van Sickle, acknowledged that such rough weather would present “a challenge” to any amphibious landing but added: “I don’t think it will be an insurmountable challenge.”

The coldest weather still lies ahead in December and January. The winds--still relatively mild--are expected to become most severe after late February, when mammoth sandstorms can darken the sky and ground air traffic.

Despite the nighttime chill, commanders insist that the weather for now remains well-suited for combat.

But on what the Marines said was the coldest night so far, Gance and others roaming an uncharted stretch of desert as part of a reconnaissance team clearly had some adjusting to do.

Supplied with five days’ worth of food, water and fuel for their long-range mission, the elite Marine team had prepared for the cold, loading their Humvee utility vehicles with poncho tops and bottoms and a stack of down-filled sleeping bags.

But the brisk wind that blew off the water and through the doorless jeep-like vehicles forced some to wrap the sleeping bags around themselves as they bounced across the pitch-black desert on patrols that lasted hours.

The elite team, although trained in mountain warfare techniques at a school in Bridgeport, Calif., remains without its own winter gear. It has been relying on what the Marines say is less adequate temporary equipment issued from military stores that remain short of winter clothing.

The change is even more dramatic on the Arab front lines, where a small supply of cold-weather gear has led soldiers to break out a hodgepodge of clothing. In a Kuwaiti camp last week, a political adviser pulled a knee-length woolen winter coat over his flowing Arab gown.

The U.S. Marine reconnaissance unit, with a motto of “Swift, Silent, Deadly,” operates in the rough, with light and fires strictly banned. This observation post is nothing more than a stretch of sand on which to sleep between two-hour watches.

Every member of the team shivered his way through the moonless night. But Gance, born and reared in Lakewood, Calif., was clearly the most miserable.

All evening long, while the team crept across the desert from one mission to another, Gance tried to make a deal with his fellow Marines: They could use his special metallic space blanket (“You know,” he urged a corporal from Ohio, “like John Glenn!”) if he could use one of their sleeping bags.

Not surprisingly, there were no takers. Gance, after coming off watch just after midnight, wrapped himself in the meager blanket and retreated to the seat of a Humvee, where he tried his best to sleep, upright but out of the wind.

By reveille at 4:30--with dawn still 90 minutes away--Gance was aching for a “heat tab,” the new, fond nickname for the desert sun.

Said Gance, “I didn’t think Saudi Arabia could ever get this cold.”