Norðurárdalur (North River Valley) is a valley in eastern Skagafjörður, Iceland bordered by the Bóluá river, which forms the boundary between Blönduhlíð and Norðurárdalur.

[2] Its northern side, at the beginning of the valley near Bólugil ravine, is called Silfrastaðafjall mountain and, farther on, takes the name Kotaheiði as it approaches the Valgagilsá river.

Many tributaries flow into it, including the Kotaá, Valagilsá, Króká, and Egilsá rivers.

[5] On July 6, 1954, there were large landslides following a heavy rainstorm that lasted 24 hours and caused extensive damage, especially at Fremri-Kot, where a landslide came to a standstill right above a residence; and at Ytri-Kot, which was already abandoned.

[6] At most there were seven farms in the Norðurárdalur area, but only three remain: Fremri-Kot, Egilsá, and Silfrastaðir.