Wildfires have almost become a year-round threat in some parts of the western United States. From Colorado to California, it feels like the blazes from last year never went out.

Flames ignited forests and chaparral virtually nonstop in 2017, and the year ended with record infernos in Southern California that burned well into 2018.

Officials don’t refer to “fire seasons anymore but rather to fire years,” Jennifer Jones, a spokesperson for the National Interagency Fire Center, told me in an email.

The NIFC reports that this year, wildfires have burned more than 5.6 million acres, about 27 percent above the average since 2008. At the moment, 15 states are reporting large fires, from Alaska to New Mexico.

Check out the sudden rapid growth of the #GrassValleyFire this weekend and others in the #WashingtonState region. Some of these #wildfires were sparked by #lightning strikes, captured here by #GOESEast's Geostationary Lightning Mapper. More imagery: https://t.co/P1F11zXUHI pic.twitter.com/dFx1hJZ5zL — NOAA Satellites (@NOAASatellites) August 14, 2018

Last month, the Carr Fire erupted in Redding, California, sending a 100-foot-high “wall of flame” through the town. The fire has already engulfed more than 207,000 acres, skipped over the Sacramento River, and is just 65 percent contained as of Tuesday. The blaze has killed two firefighters and prompted mandatory evacuations for many of the city’s 92,000 residents earlier this month. The fire has mostly moved away from the city, allowing locals to return.

Unreal aerial view of the vortex driven by super heated air rising upwards in the middle of the #CarrFire pic.twitter.com/FxWuflulpp — Brian L Kahn (@blkahn) July 28, 2018

The Ferguson Fire near Yosemite National Park has meanwhile burned more than 96,000 acres, an area about half the size of New York City, since igniting on July 13. More than 3,400 firefighters from as far away as Virginia have fought the blaze. As of Tuesday, the fire was 86 percent contained and had led to the death of two firefighters, Braden Varney and Brian Hughes.

The fire sent thick plumes of smoke and ash into the air, leading to warnings of very unhealthy air quality in the region.

#MeteorologicalMonday - We use satellite to detect where wildfire smoke is in the atmosphere. Thanks to @NOAA Earth System Research Lab we can project where its going to go and how dense it may be. Very useful for air quality, fire weather, and aviation forecasts. #vtwx #nywx pic.twitter.com/vfo7Tjh77K — NWS Burlington (@NWSBurlington) August 13, 2018

Further south, in San Bernardino National Forest near Los Angeles, the Cranston Fire ignited last month, forcing more than 3,000 people to evacuate. Authorities believe an arsonist is behind the 13,000-acre blaze. Authorities now report the fire is 100 percent contained.

Fire moving quickly. Fire jumped Hwy 243 near Idyllwild Grinding Fire. Arson suspected. One person has been detained for questioning. #CranstonFire pic.twitter.com/OhVBv9UD6e — Leticia Juarez (@ABC7Leticia) July 25, 2018

California Gov. Jerry Brown declared states of emergency for Shasta County, where the Carr Fire is still burning.

Earlier this summer, the Substation Fire near Portland, Oregon, torched 79,000 acres and forced 75 households to evacuate before dying down. It was just one of 160 wildfires sparked in Oregon this summer, though most fires were in the southern part of the state. In Colorado, wildfires have already ripped through more than 175,000 acres, and the ensuing rains have brought mudslides along the freshly denuded landscape.

And it’s likely to get worse. Many parts of the US are facing a higher than normal fire risk this year.

It’s an alarming echo of last year’s devastating fire season, which charred more than 10 million acres, making it one of the worst years in more than three decades. California suffered its largest wildfire ever, the Thomas Fire, which engulfed an area 1.6 times the size of New York City.

As firefighters take on new blazes and homeowners rebuild in the ashes, here are some things worth knowing and what we can expect for the remainder of the fire season.

Some states are already seeing worse fires than last year, and the risks remain high

A crucial thing to remember is that wildfires are ordinarily a natural phenomenon. Many parts of the US are primed to burn, and fires are vital to the ecosystem, restoring nutrients to the soil and clearing out decaying brush. Trees like the Jack pine only release their seeds after a fire. Plants like buckthorn need fires to germinate.

But the destruction from the gargantuan blazes we’ve seen in recent years is hardly natural; human activity is clearly making it worse.

For one thing, humans start the vast majority of these fires, upward of 84 percent of them. California officials have blamed a dozen of last year’s fires on Pacific Gas and Electric’s power lines. Utilities were also blamed for fires in Nevada. Arson was suspected for fires in Northern California.

Another factor is how humans use the land. People are increasingly building closer to the wilderness, blurring the line between suburbs and shrubland. That means that when fires do burn, they threaten more lives and property. Meanwhile, active fire suppression in some areas has allowed dry vegetation to accumulate, so when embers ignite, it causes a massive conflagration.

And of course, the climate is changing, mostly due to human activity. Rising average temperatures have led to western forests drying out, increasing the risk of fires. There are 129 million dead trees in California alone. Across the state, the total number of fires is trending downward, but the size of fires is going up.

But in Southern California’s fires, like last year’s Thomas Fire, scientists don’t see a climate signal just yet. The region is hot and dry year-round. Drought can actually kill off the grasses and shrubs that would ordinarily burn. As a result, the fire risks haven’t demonstrated an association with rising temperatures so far. However, modeling shows that by 2050, climate change will increase the size of burned areas in Southern California.

Despite the significant swaths of the country that went up in flames last year, there is still plenty of fuel around, even in areas that ignited last year. “Although [2017] was the second highest number of acres burned since 1960, it is a fraction of the more than 1 billion acres of vegetated landscapes in the US, so there is a lot of land left to burn,” NIFC’s Jones said.

In fact, new vegetation has already sprung up. That’s because the winter brought much-needed moisture to the drought-stricken West, despite an unusually warm winter.

Scott McLean, a spokesperson for the California Department of Forestry and Fire Protection (Cal Fire), explained that the precipitation spurred fast-growing grasses and shrubs. The searing, record-setting heat that followed this year dried out plants, leaving many parts of the West coated in tinder.

In California, fires have already burned more land and Cal Fire has initiated 200 more fire responses now than it did at the same point last year.

The NIFC reports that Utah, Nevada, Idaho, Oregon, Washington, and California all face “above normal” fire risks throughout much of their territories, as this map shows:

There are still drought conditions in Colorado, Utah, and Arizona that will likely persist even after seasonal rains, and lightning from the storms threatens to ignite new wildfires. Fire risks are lower in northern Montana and Washington state due to a wet spring.

As with last year, the fire potential will increase in the early fall along coastal Oregon and California as fast-moving seasonal winds pick up.

Even as we get better at fighting wildfires, they’re becoming more costly and dangerous

Firefighters are trying to apply some of the lessons learned from last year’s blazes. Cal Fire says it has managed to contain the vast majority of fires in its jurisdiction to less than 10 acres. But with more development in fire-prone regions, it’s getting harder to balance the demands to protect property against the need for the land to burn.

Fire officials are working with communities to explain why controlled burns are a necessary step to prevent more dangerous fires, but it makes homeowners antsy. “When you put fire on the ground, people get a little concerned,” Cal Fire’s McLean said. “It’s still an education process.”

It would also help to have policies that discourage building in the highest-risk areas. That’s difficult when the population is growing in many parts of the West and some of the cheapest land for new housing is in those regions poised to burn.

So far, this year, it seems that many of the same mistakes that have put people at risk are being repeated. In California, some residents are rebuilding in the same fire zones where homes burned last year, spurred in part by insurance payouts.

Correction: An earlier version of this article referred to the Substation Fire as being in southern Oregon. The fire was in the northern part of the state.