Because this world's axis has virtually no tilt, its seasons are determined only by its distance from its sun -- its perigee and apogee. As a result temperatures from region to region are fairly stable. Along the equator it remains mostly hot, the Northern and Southern regions stay cold and the polar regions stay frozen. In the north a crushing build up of ice pushes constantly outward away from the poles in steady moving glaciers. Further away from the axis, the mountains can build up, over centuries, towering ice caps that suck out any humidity in the air till they collapse in a gargantuan avalanche.
The only warm areas of the north are where geothermal forces exert their volatile energy. When this tremendous power builds under the mountain of ice above it can cause violent cracks, even explosions that rocket massive chunks of frozen debris through the air. The very volcanic heat that gives this area its warmer climate also can makes it quite dangerous