Environment Canada says the areas of Fort Liard and Fort Simpson can expect heavy rain throughout the day before gradually tapering off in the evening.
Both areas are expected to receive rainfall of about 50 to 80 mm.
EC warns that heavy downpours can cause flash floods and water pooling on roads.
Localized flooding is also possible in low-lying areas.
Residents are being asked to watch for possible washouts near rivers, creeks and culverts.