What is the weather like in Alaska in spring?

From the text:

In summer the road here would have been sketchy but passable; now it was made unnavigable by a foot and a half of mushy spring snow. Ten miles from the highway, worried that he’d get stuck if he drove farther, Gallien stopped his rig on the crest of a low rise. The icy summits of the highest mountain range in North America gleamed on the southwestern horizon.

When he dropped McCandless off on the Stampede Trail, the temperature was in the low thirties—it would drop into
the low teens at night—and a foot and a half of crusty spring snow covered the ground.

By mid-May the sun was circling high in the heavens, flooding the taiga with light. The sun dipped below the northern horizon for fewer than four hours out of every twenty-four, and at midnight the sky was still bright enough to read by. Everywhere but on the north-facing slopes and in the shadowy ravines, the snowpack had melted down to bare ground, exposing the previous season’s rose hips and lingonberries, which McCandless gathered and ate in great quantity.