Festuca aloha is a perennial, cespitose grass reaching heights of 45–70 cm. The culms are erect and slender, about 1 mm in diameter. Leaves are simple and alternate, with vegetative shoot blades measuring 22-33 cm long and 1-1.5 mm wide, displaying an erect to pendant form. The lower surfaces are glabrous and smooth, while the upper surfaces have hairs up to 0.1 mm long along the ribs. The margins are involute, with 13-16(-20) prominent ribs on the larger vascular traces, interspersed with smaller ribs on the secondary and tertiary veins. Sheath margins are fused at the base for 1-2 mm, overlapping more than half their length below, initially sparsely villose but becoming glabrous at maturity, with a purple-brownish base turning greenish above. The flowers are 8-11 cm long and 2.5-4 cm wide panicles, erect with a smooth axis and peduncle, featuring 34-66 spikelets, mainly at the tips of branches. The panicle branches are 2(3) per node, with the basal ones being 4-6 cm long, roughly half the length of the panicle, and range from smooth proximally to scabrous distally. Spikelets, measuring 8.2-13 mm long and 3.5-6.0 mm wide, contain 4-6 flowers and are broadly lanceolate, pale green, and occasionally purple-tinged. Pedicels range from 1 to 3.5 mm long. Glumes are lanceolate, green with narrow scarious margins, and acute apex; the lower glumes are 3.6-4.2 mm long, and the upper ones are 5.2-5.5 mm long. Lemmas are 5.8-8.0 mm long, green or purple at the apex, mucronate to awned, with a 0.5-1.1 mm long awn. The ovary is superior and densely hairy on its upper third. The fruit is a caryopsis, and it occurs on steep mountain slopes and volcanic cliffs.