An extreme, ongoing heat wave in Western North America began affecting much of the Pacific Northwest and Western Canada in late June 2021. The heat has affected northern California, Idaho, western Nevada, Oregon, and Washington in the United States, as well as British Columbia, and, in its later phase, Alberta, Manitoba, the Northwest Territories, Saskatchewan, and Yukon, all in Canada.[2] It has also affected inland regions of central and southern California,[3] northwestern and southern Nevada and parts of Montana and Wyoming, though the temperature anomalies were not as extreme as regions farther north.