Hundreds of wildfires are burning across the eastern United States, focused on the central and southern Appalachians from West Virginia to north Georgia.

Unusually warm and breezy conditions associated with a powerful fall heat spell helped intensify the fires in recent days. Winds associated with a cold front could fan the flames and allow these blazes to expand into the weekend.

While it’s around the peak of the fall fire season, this year’s activity is more expansive than typical and is driven by abnormally dry conditions. Across the southern Appalachians and into Virginia’s Blue Ridge Mountains, drought is rated severe to extreme by the federal government.

Some rain may fall in the region Friday, but not in significant amounts. Any more meaningful rain may be at least a week away.

Fires burning across multiple states

The fires are burning across a broad region, including at least 80 in West Virginia, 60 in Kentucky and dozens in Tennessee, Virginia, North Carolina and Georgia.

Burn bans are in effect for most of the zone with active fires. States of emergency have recently been declared in Virginia, North Carolina and Kentucky. Firefighters from around the country are being dispatched.

A majority of the fires have been caused by humans, either through local burns that escaped control, arson or other various activities. The very dry conditions ensure that any blaze that starts has a good chance to survive. Add in gusty winds, and flames can scorch large tracts of land without much effort.

Some of the bigger fires to erupt in the southern and central Appalachians include:

— Quaker Run: About 3,000 acres have burned near and into Shenandoah National Park near Luray in western Virginia. Numerous trails in the area are closed because of fire and smoke risks.

— Collett Ridge: Now up to 4,300-plus acres and entirely uncontained, this blaze in southwest North Carolina was started by lightning in late October.

— Sidney: One of numerous fires in southeast Kentucky, it’s nearing 1,500 acres and continues to burn out of control.

— Steep Valley: An 800-acre fire in south-central West Virginia, it grew from 150 to 800 acres between Tuesday and Wednesday.

Smoke is compromising air quality

Because of smoke from the fires, air quality was diminished Thursday in much of Virginia, the Carolinas, Georgia and parts of Florida, according to AirNow, the federal government’s air monitoring website. Most spots in these areas were seeing code yellow levels — defined as moderate air quality — but some locations particularly close to the fires have seen air quality tip into unhealthy categories.

At least some smoky haze covered a large part of the eastern United States south of the Great Lakes and New England Thursday, although it was largely suspended in the air rather than near the ground where it can meaningfully degrade air quality.

The smoke has mostly avoided the Interstate 95 corridor from Washington northward, but some could drift in that direction on Thursday.

It’s peak fire season

Along with the spring, fall is one of the two times of year when fires are most common in the central Appalachians and surrounding locations. The West Virginia Division of Forestry notes that the fall season runs from October through December.

The National Weather Service Storm Prediction Center map of where blazes are most common at this time of year, shown above, highlights much of the area where most of the bigger blazes are currently burning. But this year’s activity covers more territory and that can be connected to rainfall deficits.

Expanding drought - reaching extreme levels in Virginia’s Blue Ridge Mountains - is helping to fuel the large fire in and around Shenandoah National Park.

Outside of West Virginia, drought covers much of the central and southern Appalachians. While West Virginia is largely drought-free, it has been quite dry there the last month or two. In some parts of the Southeast, it has been months since the last rainfall of one inch or more.

Hope ahead?

Drier than normal weather is projected to persist in much of the fire-scorched zone for the next week or so.

There are increasing hints of a more active southern jet stream, which could spawn storms traveling across the southern United States around the week of Thanksgiving. Increased storminess across that region is a typical consequence of the El Niño climate pattern, which is forecast to strengthen into the winter months.

While El Niños tend to bring wetter-than-normal conditions to the southern United States, appreciable precipitation is less certain to the north from the Mid-South to the Ohio Valley and central Appalachians. Even so, the wildfire risk should diminish heading into winter because of lower temperatures.