On Monday the fire ignited a commercial building downtown that billowed with smoke containing toxic ammonia gas.
The Sleepy Hollow Fire ignited in brush just outside the central Washington city Sunday afternoon and doubled in size overnight, said Chelan County officials.
Wenatchee, near Lake Chelan, a popular destination for people from southern British Columbia, is 230 km south of Osoyoos, B.C. and about 200 km east of Seattle, Wash.
"If you have plans to come down I would put the plans on hold and let things get under control here first," said Trooper Brian Moore of Washington State Patrol in Chelan County.
At least 24 houses and additional outbuildings have burned in a subdivision north of town, said Moore.
The large wildfire sparked smaller fires in several commercial buildings downtown, including one that burned releasing ammonia gas.
"That's our biggest concern right now, and that's where most of our resources have gone to," said Moore Monday afternoon.
Several blocks of downtown, along the Columbia River were under a shelter-in-pace advisory. People in safe locations are asked to seal their doors and windows and turn off their air conditioning, while others were told to leave immediately.
Winds picking up Monday afternoon
At least eight strike teams were working the 1,200 hectare brushfire Monday, said Moore.
Sweltering heat above 37 C, tinder-dry brush and strong winds fueled its growth overnight, and winds were expected to pick up Monday afternoon.
"Afternoon winds in the Wenatchee valley are usually the worst as the day warms up," said Moore.
The only reported injuries from the Sleepy Hollow are minor, with firefighters being treated for smoke inhalation and heat exhaustion.
Officials know the fire started in brush on the edge of town but they are still trying to determine what sparked it.
Hundreds of firefighters were on the scene and more, including state firefighting resources, are heading there Monday.
MAP: Wenatchee, Wash.