Looking back through the attendance figures, the highest average home attendance between 1962 and 2000 was in 1976 with an average of 9,150. The lowest was in 1991 (4,846), when the Sioux played 4 home games, including Morningside, Augustana and Moorhead State.
SDSU also plays outdoors and they have seen an increase of between 40-50% in attendance over their old D2 days. Granted Grand Forks is colder than Brookings, but people from North Dakota are tougher.