The choppers deployed a day after Gov. Chris Gregoire signed an emergency declaration for all the state's counties east of the Cascade Mountains.
Seven large complexes of fires have burned across around 230 square miles of parched land east of the Cascades, where some areas have gone without any measurable rain for weeks. More than 3,000 firefighters across the region dug lines and burned dry grass and brush in the path of the fires.
One of the largest fires - the Wenatchee River Complex in Chelan County - is 10 percent contained, but crews there said they had success on Thursday. On Friday, crews with air support worked to cool down hot spots.
The two helicopters are a CH-47 Chinook helicopter with a 2,000-gallon water bucket and five-person crew, and a UH-60 Blackhawk helicopter with a 660-gallon water bucket and four crew members, the National Guard said.
The pilots and crew are members of the Washington Army National Guard's 66th Theater Aviation Command, which also aided last month in the Taylor Bridge fire by dumping 632,000 gallons of water.
Heavy smoke continued to cover much of the region early Friday, eroding air quality but serving a positive sign of low winds and fires that weren't quite so active.
Cooling temperature is forecast to move into the region over the weekend. But there is no sign of rain in anywhere near in the forecast. Firefighters hoped to take advantage of the favorable conditions before the weather shifts again.
On Friday, authorities lowered the evacuation warnings to the lowest level for nearly 160 homes in the Wenatchee area, said spokesman John Kruse.
About 10 miles from the Grand Coulee Dam, two fires grew to a combined 91,883 acres, or 143 square miles. The fire was 63 percent contained by late Thursday.
Another fire burning 17 miles southwest of Creston was 40 percent contained. That fire has blacked 24,500 acres, or about 38 square miles, some 50 miles west of Spokane.