USHUAIA, Argentina (AP) _ The temperature's rising, the sun's peeking out over the mountaintops and it promises to be another scorcher in Argentina's Deep South: That is, a day when the mercury makes an appearance above freezing.

This may be the Tierra del Fuego _ Spanish for the ``Land of Fire'' _ but on South America's southernmost tip, about 115,000 inhabitants are trying to beat the snow, ice and a bone-chilling cold a world away from North America's cruel heat wave.

Natalie Pasarela, 15, leashed her Alaskan sled dog Negra to a rope tied to her snowsuit and took off on cross-country skis across a winter wonderland.

``Hup! Hup! Pull!'' she shouted joyfully as Negra _ a 2-year-old with coal-black fur and pale blue eyes _ lunged forward, towing Pasarela at breakneck speed over a snowy mountain trail.

Nearby, her father, Jorge, 47, split stout logs with an ax and tossed them into a fire roaring in an oil drum. Cross-country skiers coming off mountain trails gulped hot coffee close to the flames.

Here in Ushuaia, the southernmost city on earth, 1,945 miles south of the Argentine capital of Buenos Aires and just 435 miles north of Antarctica, it's deep winter. Temperatures hover around freezing every day during the season and plummet far below that on most nights.

A place whose very name evokes fear of the elements, isolation and loneliness, Tierra del Fuego is a sprawl of mountainous islands, sea channels and cliffs locked in a chill all winter.

Summer in the Southern Hemisphere _ which comes as Americans and others in the Northern Hemisphere are stumbling through winter _ is mild and blissful. Temperatures range into the mid-80s and the sun shines for all but a few hours.

Soaking up what little warmth 6 1/2 hours of daylight afford, children this week pelted each other with snowballs or whisked down icy hills on plastic sleds, packing as much activity as they could into a day that began with a 10 a.m. sunrise. After a late lunch, the day slides toward sundown.

Some complain that temperatures above freezing ruin the fun.

``The snow's too icy,'' grumbled Abelardo Cano, 14, trying out his snowboard with a group of friends, all from Ushuaia, who are enjoying a two-week winter school vacation.

Each year, tens of thousands of people visit Ushuaia, primarily in the warmer summer months, dwarfing its year-round population of 45,000. But areas around Ushuaia and elsewhere in the Argentine portion of Tierra del Fuego _ its islands are split with Chile _ are now being promoted as a destination for skiing, snowmobiling and dog-sledding.

In Ushuaia, weather-worn houses climb the rocky slopes from the icy, blue Beagle Channel, reflecting the rays of a sun that barely skims the horizon and lingers briefly on jagged snow-topped peaks.

In the mushy, icy streets, taxis clink along with chains on their tires, prowling for passengers as snowplows clear away several inches of snow that fell earlier in the week.

The sun's feeble warmth brings a steady drip-drip from 10-foot icicles hanging from a gray mountain face. Loads of snow slip from the tops of A-frame homes and come crashing down.

Mercedes Lescano, a 34-year-old mother of four, said when temperatures creep above 32 she lets her kids romp in the knee-deep snow all day.

``Let's just hope this warm weather holds. It's so much easier keeping these little guys outside the house than in,'' Lescano said, noting the long winter nights when children are penned indoors.

Asked if she was aware of the heat wave sweeping across the Northern Hemisphere, one youngster, 11-year-old Estefania Firma Paz, said, ``Yeah, they told me about it in school. When it's winter here, it's hot up there.''