The blaze threatened more than 200 homes and damaged a few outbuildings in Chelan County near Entiat, roughly midway between Seattle and Spokane.
Residents of about 40 homes have been told to evacuate, fire operations spokeswoman Laurie Dowie said Friday. Also, a stretch of highway south of the blaze has been closed.
Weekend forecasts call for a prolonged heat wave with high temperatures in the triple digits in the area, prompting concerns the fire could grow.
Because of the risk, state officials extended an outdoor burn ban to include all 13 million acres of lands that the state protects.
A burn ban, which has already been in effect in Eastern Washington, now includes Western Washington. The ban is in effect through Sept. 30.
Meanwhile, a wildfire burning fewer than 2 square miles near Spokane stopped growing overnight, spokesman Chuck Turley said.
Turley said firefighters working the blaze near Ford in Stevens County hope it doesn't flare up in the hot, dry conditions forecast for the weekend.
"As heat hit this area some of the areas will have a tendency to rekindle," Turley said.
He said the Lake Spokane campground has been closed to the public.
Officials are urging people to be vigilant as hot and dry conditions increase fire risks throughout the state.
The causes for both fires are under investigation.