Lasionycta impingens is a moth of the Noctuidae family. It occurs from southern Yukon to Colorado. It is diurnal. Adults are common in alpine tundra. It feeds on nectar of a Penstemon species on the Beartooth Plateau, Montana, as well as on Mertensia paniculata and a Senecio, likely Senecio lugens at Pink Mountain, British Columbia. Adults are on wing in July and August.