PORTLAND, Ore. (AP) - Firefighters are getting some help from the weather in their battle against Oregon's largest wildfires.

Officials said Friday that crews have slightly increased containment of a blaze torching the scenic Columbia River Gorge.

Cooler temperatures, higher humidity and light rain are expected to provide a lift to firefighters this weekend. Four houses have been destroyed since the fire began last weekend. Investigators believe it was started by a teenager playing with fireworks.

Rain slowed several wildfires in southern Oregon, allowing some evacuation notices to be lifted Thursday.

Air quality also improved slightly in the smoke-smothered region.

The Mail Tribune reported Friday that Roseburg, Grants Pass and Cave Junction registered "moderate" air quality, while air quality stations in Ashland, Medford and Shady Cove recorded air that was unhealthy for sensitive groups.

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