The rhododendrons pictured against Mt. Hood in Oregon are members of the Ponticum series, R. macrophyllum.* The plants are near the timberline at about 2700 ft. elevation and bloom in June.
*R. macrophyllum by Morton E. Peck in "The Rhododendron Yearbook" by the American Rhododendron Society, 1947, vol. 3, page 87.