Not so long ago, Yakutsk looked like what one would expect of a town in Siberia's far northern reaches: a jumble of wooden huts, huddled together in groups as if for warmth and half buried in the snow with only thin wisps of smoke to show that people were inside.

Large sections of the city still are pretty much that way, a glimpse of life in centuries past without plumbing and only simple stoves for fending off temperatures 50 or 60 degrees below zero. Unpaved roads turn into a muddy slush in spring and swamps in nearby forests breed mosquitoes with a sting that rivals even winter's icy bite.

But the grim and rustic conditions - once thought suitable for an outlying trading post where Czarist exiles, and later their Stalin-era counterparts, mingled with illiterate native trappers - are no longer acceptable. Yakutsk is emerging as the hub of what the Soviets want to be a region of intensive energy and mineral development. Planners see a metropolis in the future that reflects that stature.

At first sight, those hopes seem far off. Although a major newtrans-Siberian rail line is being built further south, Yakutsk is hundreds of miles from it and has no railway. Vital river routes are frozen for much of the year. Nor are there any important roads. Only air communication is possible in the winter and fogs often intervene.

The cost of building is very high, more than twice as much per square foot as in Moscow, according to the city architect, Valery Beketov. To provide protection from the cold, walls must be twice as thick as they ordinarily are and windows need triple panes. The pace of construction in winter months is understandably slow. At minus 58 degrees, it stops altogether.

Some projects clearly find resistance from Soviet central authorities.

"What costs 6 million rubles in Sverdlovsk costs 15 million rubles here," said one frustrated planner. "The Ministry of Culture, for instance, wants to know why it should build a concert hall in Yakutsk when it could build one in Sverdlovsk, Vladivostok and Vilnius for the same money."

Yet for all the isolation and complexities, local specialists claim that Yakutsk is growing at a considerably faster rate than had been expected. It was barely 10 years ago that the first concrete prefabricated buildings of the standard Soviet type were erected. Now it is claimed that nearly half the city's 150,000 people are living in modern apartments.

Recently a nine-storey building, the first in Yakutsk with a passenger elevator, was opened; on the drawing boards are ambitious designs for semi-circular high-rises with up to 20 stories. By placing shopping in ground floor arcades, architects hope to minimize the effects of cold.

There are also designs for covered walkways connecting nurseries or schools with residences as well as stores but a proposal for a completely enclosed neighborhood was rejected because it was deemed psychologically unacceptable. The aim is to make Yakutsk as much like other Soviet cities as possible in spite of the extreme climate.

Probably the most important technical breakthrough for developing Yakutsk was the placing of all structures on stilts pile-driven into the frozen ground rather than flush against the surface. A few feet of earth would melt under buildings in the warm summer months and they would sink up to their bottom-floor windows. That danger precluded all but the most modest construction and gave the town its topsy-turvy look.

Under the system that came into use after World War II, steam is pumped into holes drilled into the solid ground.Concrete pilings about 25 feet in length are then laboriously inserted with special cold-proof cranes. They freeze into place. The process is expensive, but it works, and specialists are now trying to apply similar principles to the laying of rail tracks and roads.

The next important step was the local manufacture of heavy concrete panels so that construction could be done on a mass scale. An outsider's observation, however, is that the weather punishes buildings here to such an extent that they start looking shabby almost immediately, even though engineers say they are structually solid.

Joseph Danziger, chief of Yakutskstroi, which is responsible for most construction, insists that the prefabs are made to last a hundred years, although he acknowledges that major repairs will have to be made every 10 or 15 years. As technology improves, he said, the facades will start to hold up better.

Another problem is severe drabness. The old wooden huts with carved and gaily painted window frames had a picturesque charm, even though they lacked modern amenities. For that reason, as well as a preference for privacy, some families choose to stay in them.

Newer sections of Yakutsk, like those of other newer Soviet cities and towns, are barren and colorless. The situation is compounded here by a paucity of greenery that makes the landscape seem lifeless. The winter snow gives everything a white layer, but the summer is said to be flat and dry. Yakutia gets only about nine inches of rain, making it difficult to get anything to grow.

Some hothouse planting is being tried to expand the very limited agricultural output and eventually flowers may be added.Welcoming two American visitors to Yakutsk the other day, Elena Pankova of the Permafrost Institute, a lifelong resident of Yakutsk, said that it is customary in Russia to welcome people with flowers, but conditions being what they are, all she could offer was a small slip of edelweiss.

The variety of difficulties already overcome is so great, however - automobiles now get double-glass panes with air sandwiched between them to prevent frosting over, apartments have elaborate central humidifiers to counteract dryness, steam heating makes the indoors cozy on the coldest days - that it seems certain that remaining problems will be solved as well.

Soviets like sweeping comparisons, and one of the favorite ones here is that whereas the rest of the country is now 140 times more economically developed than before the Bolshevik revolution, the figure for Yakutsk is 400 times. Whatever the numbers, there is no doubt that one of the world's last great wild areas is being tamed.