Wrangell (population 2,127) and Petersburg, Alaska (3,398) are located close to the mouth of the river, but are not within the drainage basin. Forests cover about 50 percent of the basin, and most of the remainder is covered by treeless tundra or permanent ice and snow. About 73 percent of the basin in BC is considered to be in a wilderness or semi-wilderness condition. Due to the rain shadow effect of the Coast Mountains, the interior Stikine basin has a much drier and more variable climate than the coast. Wrangell experiences a humid continental climate, with monthly average temperatures ranging from a low of in January to in July. The average annual precipitation is . Dease Lake, about northeast of Telegraph Creek, experiences a subarctic climate with monthly average temperatures ranging from in January to in June, and an average annual precipitation of just . In the interior, freezing temperatures are observed in six months of the year. Course The headwaters of the Stikine are in the Spatsizi Plateau, the southeasternmost sub-plateau of the Stikine Plateau. Originating on Mount Umbach above sea level in the Spatsizi Plateau Wilderness Provincial Park, it flows northeast through a chain of small lakes, including Tuaton and Laslui Lakes, then turns north, following a meandering course along the western foothills of the Omineca Mountains and the Cassiar Mountains. The river enters Stikine River Provincial Park, turning west at the confluence with the Chukachida River, then northwest at the confluence with the Spatsizi River. At the confluence with the Pitman River, it turns due west again, now flowing along the south side of the Three Sisters Range, then receives the Klappan River from the south. North of Iskut, it is crossed by BC Highway 37 (Cassiar Highway), the only road bridge across the Stikine. Below Highway 37, the river enters the Grand Canyon of the Stikine, a deep canyon cutting between the Tanzilla and Klastline Plateaus, both sub-plateaus of the Stikine Plateau. Here, it flows much more swiftly, falling in between Highway 37 and Telegraph Creek. At one point the channel narrows from wide to just wide, a place known as the "Tanzilla Slot", where it squeezes between sheer walls of volcanic rock. After receiving the Tuya and Tahltan Rivers from the north it flows through Mount Edziza Provincial Park, home to the dormant stratovolcano Mount Edziza, the central feature of the Mount Edziza volcanic complex.