ROSS LAKE, WA (MyBellinghamNow.com) – Fire crews worked through adverse smoke conditions over the weekend in an effort to contain a blaze in the North Cascades.

The National Parks Service says that a smoke inversion made things difficult above the Perry Fire, especially for aerial water drops and surveillance over the weekend.

An inversion generally occurs when smoke from a wildfire becomes stagnant.

Sparked by lightning in late August, the Perry Fire is estimated to have burned 1,557 acres on the west side of Ross Lake.

Boat crews are among those working to keep structures standing in the Little Beaver and Silver Creek Campgrounds. At least two helicopters have since been deployed for additional water drops and aerial support.

Smoke conditions have improved as temperatures in the North Cascades are forecast to cool.