Using a moderate temperature will ensure that the salmon stays moist. Dressed/marinated salmon: Bake at a lower temperature like 350 or 375°F to prevent the sauce from burning. Fold over aluminum foil tightly to make packets; make several holes in top of packets with a fork to allow steam to escape. Dry seasoned salmon: Bake at higher temperatures for shorter periods to get moist fish with a crispy exterior. Bake at 375 degrees for 15 to 20 minutes. Top fillets evenly with onion slices, diced butter, lemon slices and brown sugar. Arrange packets on an ungreased baking sheet. To add some extra browning and flavor to the surface, broil the salmon for 3 to 4 minutes. Bake the salmon at 375ºF (191ºC) for the first 10 to 12 minutes, until it reaches 125ºF (52ºC).