The soft green forests and flowery meadows are in sharp contrast to the rocky walls of the crater and the bare rock formations which poke above the rim. Wildflowers blanket the park meadows and forest floor for most of the summer. They are some of the 600 species of plants which have colonized the region since the volcano's ash covered the slopes for many miles around. The forest is primarily mountain hemlock and Shasta red fir, with stunted and twisted whitebark pine at the rim. Down from the rim, a more temperate forest of ponderosa pine and lodgepole pine is found.
Winter provides a stark, white environment.
A year's snowfall on the rim can be as much as 50 feet, and because of the moderate Oregon climate, the lake hardly ever freezes over, using stored heat from its lower depths. The last time the lake developed a thin sheet of ice was in 1949. While snow falls in October and doesn't recede until May, the south park road is kept open for visitors, who come to look at the lake in this special time of year. Park rangers open a gate, at 8 a.m. daily, and close it at sunset. Snowmobilers can enter the park at the north gate, and drive to a vista point overlooking the lake.