Western Washington state is one of the wettest places in the country. In the North Cascade mountains and on the Olympic Peninsula, lush cedars, ferns and mosses form classic Pacific Northwest rainforests. But even here, climate change is making wildfires more likely. And the state is figuring out how to respond.

“It used to be that it really wasn’t until mid-August that fuels dried out in western Washington,” said Derek Churchill, a forest health scientist at the Washington Department of Natural Resources. “Now it’s July or earlier.” In fact, last month human activity started a wildfire in the Olympic national forest. As of Tuesday, it had grown to more than 5,100 acres and some campgrounds were under evacuation orders.

Fire in Western Washington is not a natural part of the ecosystem’s annual rhythm, as it is for drier grasslands and pine forests in the eastern part of the state. Instead, every few hundred years, a megafire strikes, burning hundreds of thousands of acres, replacing whole forests with slopes of charred spindles.

But global warming is changing fire patterns in the state. Washington’s summers are growing longer, hotter and drier, resulting in an extended fire season with more desiccated fuel available. Paired with swelling populations throughout Puget Sound, it’s a recipe for more frequent annual fires.

More frequent fires in turn increase the odds, slightly but surely, that a megafire will occur. The only question is timing.

As a result, forest managers and firefighters are keeping a wary eye on smaller fires like the Bear Gulch fire currently burning in the Olympics. The last megafire razed western Washington in the early 20th century. More recent fires have been smaller, but concerning. In 1978, more than 1,000 acres burned in the Hoh Rainforest, which can receive as much annual precipitation as the wettest reaches of the Amazon Rainforest. In 2015, more than 2,000 acres of the Olympic rainforest caught fire along the Queets River before fall rains extinguished it.