WITH U.S. FORCES, SAUDI ARABIA, SEPT. 2 -- The searing heat of the Saudi Arabian desert sun melts radio wires, turns metal handles on tanks into flesh-charring pokers and shorts sensitive electronic gear critical to the operation of many weapons.

For military equipment that can withstand the heat, there's the sand -- sand as fine as powdered sugar, sand that eats through the sprockets of tank treads, jams machine guns and seeps past the filters of aircraft engines.

The high-technology U.S. military has come under brutal assault from the harsh summer desert, with the blistering heat and corrosive sand reducing the effectiveness of everything from the sophisticated electronic jammers designed to protect ground-attack planes in combat to the radar scopes on the computer-guided Patriot air-defense missile system.

"The weather causes a lot of problems -- equipment just quits working," said Airman 1st Class Kimberly Childress, who maintains classified communications systems for the Air Force's A-10 Thunderbolt II antitank aircraft. "All you can do is wait for it to cool off."

But even as American troops struggle to adapt sophisticated weaponry to the cruel summer climate, the desert will soon enter the traditional Middle East combat season -- the period between mid-September, when the heat begins to subside, and the onset of winter, when temperatures drop below freezing and bitter winds sweep the sands.

For the military mechanics, tank commanders and missile technicians here, the initial weeks of Operation Desert Shield have forced them into a crash course in desert warfare.

If, for instance, the A-10, a gangly-looking ground-attack plane popularly known as the "warthog," is sent into battle against Iraqi tanks, it will depend on cylindrical pods under its wings to jam the signals of enemy air defenses. But weapons loaders toiling under the midday sun at an air base here said the heat renders the jammers useless after about an hour of operation. A typical sortie against hostile tanks would likely require far more than an hour's protection.

"The equipment gets hot, the jammer overheats," said Sgt. Lisa Weis, a weapons loader with the 354th Tactical Fighter Wing based at Myrtle Beach, S.C. "You've got to shut it down after about an hour."

The Patriot missiles, which are being relied on to protect critical military sites from attack by Iraqi Scud-B missiles and aircraft are controlled by computer equipment housed in air-conditioned vans. But the sun is so unrelenting on the vans' metal shells that it drives up the temperature inside.

"Every now and then, there is a glitch that makes the {radar} scope look blank," said one missile technician. He said that in the event of an attack, the computers are supposed to override any radar screen malfunction or other problem that might hinder a human operator and track an incoming missile on its own.

Less sophisticated equipment is no less vulnerable to the hellish heat, which sometimes climbs to 130 degrees. Army infantry troops quickly discovered that the heat melted radio wire and burned out transmission equipment. Now soldiers cover the radios with wet burlap to keep them cool.

Metal on everything from tanks to trucks becomes so oven-hot that troops are forced to wear thick gloves to protect their hands. Helmets turn into Dutch ovens. On the day the 82nd Airborne Division was ordered into the desert, one member of the outfit barbered 1,000 of his fellows to the quick in the hope that bare scalps would fare better in hot helmets than full heads of hair.

The sun pounds the space-age skin of Air Force F-15 Eagle fighter jets, expanding the metal and creating fuel leaks, according to crew chiefs who service the aircraft.

The heat also has forced the Marine Corps to change all the oil in its tanks to a different grade. Marine officials said they were surprised to discover that their prepositioned ships -- which are stocked with tanks, other weapons and supplies at far-flung bases in readiness for conflict under various conditions -- came equipped with oil unsuited for desert operations.

For some equipment, the abrasive effects of the desert sand and salts are even more damaging than the heat. The velvety sand, whipped by the desert wind, is creating serious maintenance problems for virtually every U.S. military unit here. The grit seeps, for instance, into the belts that feed bullets into M60 machine guns. "It causes it to jam," said Pfc. Tim Barnett. "It doesn't work. . . .Sand gets into all the moveable parts."

Most combat troops here say that if they're not on the job or eating or sleeping, they're cleaning weapons. One Marine recently sat outside his camouflaged desert bunker cleaning the barrel of his machine gun with a toothbrush. Barnett said the troops clean the weapons daily, usually after dark when the winds have calmed.

Because of the omnipresent sand, the Army flushes the engines in its Apache attack helicopters daily and cleans the air filters on its tank and truck engines far more frequently than when the equipment was used back home in Texas or Georgia.

Many U.S. troops have trained at the military's expansive National Training Center in the California desert and during earlier Middle East operations, which have provided some indication of the difficulties of working in the heat and sand. Training missions conducted in Egypt revealed that helicopters operating in a desert environment require twice the maintenance hours as those in a European or American climate.

And during the escort missions for reflagged Kuwaiti tankers plying the Persian Gulf two years ago, Navy and Army mechanics had to replace aircraft parts three times more often than usual because of the wear and tear. Aramco oil officials, with about 50 years of experience operating heavy equipment in the Saudi desert, say that heat and sand are the chief cause of breakdown in their machines.

But the sun and sand affect Iraqi troops and equipment as adversely as they do the American troops, U.S. commanders note. Throughout the eight-year Iran-Iraq war, both sides launched most of their attacks just before daybreak while the temperatures were bearable and the winds relatively still.