| Mount Castner | |
| Elevation Ft: | 5535 |
| Elevation Ref: | [1] |
| Prominence Ft: | 585 |
| Isolation Mi: | 1.41 |
| Range: | Chugach Mountains |
| Parent Peak: | Peak 6140 |
| Location: | Chugach National Forest Valdez-Cordova Borough Alaska, United States |
| Map: | USA Alaska |
| Label Position: | left |
| Coordinates: | 61.19°N -147.5839°W |
| Coordinates Ref: | < |
| Topo: | USGS Anchorage A-2 |
Mount Castner is a 55350NaN0 elevation glaciated summit located 440NaN0 west of Valdez in the Chugach Mountains of the U.S. state of Alaska, on land managed by Chugach National Forest. It is situated at the head of Ranney Glacier and Dartmouth Glacier. Although modest in elevation, relief is significant since the mountain rises from tidewater at Unakwik Inlet and College Fjord of Prince William Sound in approximately three miles. The mountain's name was applied in 1910 by Lawrence Martin, and officially adopted by the United States Geological Survey. This peak's name honors Joseph Compton Castner (1869–1946), who was with Captain Edwin F. Glenn during the exploration of this area in 1898.[2]
Based on the Köppen climate classification, Mount Castner is located in a subarctic climate zone with long, cold, snowy winters, and mild summers.[3] Weather systems coming off the Gulf of Alaska are forced upwards by the Chugach Mountains (orographic lift), causing heavy precipitation in the form of rainfall and snowfall. Temperatures can drop below −20 °C with wind chill factors below −30 °C. This climate supports the Meares and Yale Glaciers surrounding this mountain. The months May through June offer the most favorable weather for climbing or viewing.