THE DALLES, ORE. — Walls of fire up to 30 feet high swept across the dry countryside of northern Oregon in mid-July, destroying an estimated $5 million worth of soft white wheat just a few weeks into harvest.

With the major fire now under control, damage appeared to be limited to about 3% of Oregon’s $186 million wheat crop. But other small fires continued to burn, and hot, dry conditions may lead to further incineration of standing wheat before the region’s harvest concludes.

“Down in the Dalles area and south from there, they’ll probably wrap up in mid-August,” said Steve Yorke, a merchant with Northwest Grain Growers. “Other areas, like up north in the Spokane area, the Palouse region, they haven’t even started yet. They’ll probably continue through that first week in September. We always say harvest goes from about July 1 through the first couple weeks in September.”

The winter wheat harvest in Oregon was 32% completed as of July 22, the U.S.D.A. said, ahead of 28% a year ago and slightly behind 33% as the 2013-17 average for the date.

Although lightning fires have popped up around the state, the most severe blaze was believed to be human-caused. The Wasco County Sheriff’s Office has initiated a criminal investigation into the Substation Fire, ignited July 17 on private land southeast of The Dalles, a city along the northern Columbia river border with Washington.

The blaze developed into the nation’s top priority wildfire, claimed at least one life and threatened farmland in north central and northeast Wasco and far western Sherman counties at the onset of the soft white wheat harvest. Strong winds sent embers far across the leading edge, threatening farmers who battled the fire with water tanks mounted on pickup trucks and tractors. The fire generated its own winds as well.

“It’s devastating to that whole area where it came through,” said Kevin Gray, general manager of Morrow County Grain Growers, Inc., with headquarters in Lexington, Ore. “And the speed at which it came through, we weren’t able to get control of it before it got into wheat. It just grew so fast and so quickly that it only makes sense that it would get into standing wheat.”

Some estimates say 1.5 million bus of wheat may have been burned, nearly half of the Wasco County crop, worth more than $5 million, and consisting largely of soft white wheat, much of which is sold to the Philippines and Japan for use in sponge cakes, noodles, crackers and cookies.

While estimated losses are a small percentage of the Northwest’s 260-million-bu annual production, individual farms may see losses totaling $250,000 or more.

 “From a financial standpoint, it definitely would have been better had the grain been harvested, put into a bin and marketed through the market channels than to take crop insurance on this crop,” Mr. Gray said. “That crop that got burned up was excellent. Good quality, really high yields. It will have an impact.”

In 2017, Wasco County produced about 3 million bus. But the quality and yields seen in the nascent 2018 harvest had some grain professionals making the case that the Wasco crop would have been 20% to 25% bigger than it was last year — about 4 million bus.

“They did lose some acres, definitely,” Mr. Yorke said, “but I don’t see it doing much to the price” of wheat due to the strong yields. Crop insurance “might not cover the total amount because yields were so good this year.”

The Pacific Northwest spring season included significant rain and good growing conditions, not only for wheat but for brush and underbrush. Heavy growth became fuel for the fires when dry weather set in during summer. Producers and support industries were taking extra precautions, including keeping quadtracs and other four-wheel-drive vehicles hooked up to disk rippers nearby to be able to try to work the ground and create fire lines to stop fires from spreading. Loaded tender trucks are at the ready.

“Everybody is being cognizant of the weather conditions and the heat prior to going out into the field and starting to harvest,” Mr. Gray said. “But at the same time, you’ve still got to get the crop harvested.”

Fire lines typically are constructed about 40 to 50 feet wide as time allows before a fire advances. That width wouldn’t have stopped the Substation Fire, which was seen jumping over 60- and 100-foot-wide fire breaks.

“Last week was kind of the exception to the rule,” Mr. Gray said. “Typically, you don’t see that type of behavior. It was the heat, it was the wind, it was the dry conditions, it was the low humidity. There were just a number of factors that played into it last week, and it’s unprecedented what this particular fire did.”

The fires may affect wheat that survived in close proximity to the destroyed fields.

“Smoke can definitely get in the kernel and cause an odor, and there is a discount for odor, when you get it tested and graded down at the lab in Portland,” said Mr. Yorke in St. John, Wash. “I haven’t heard of any smoke odor damage yet, but that is definitely a possibility that an odor discount could be taken at the export facilities.”

Looking further ahead to next season, the charred fields will take time to rebuild and return the wheat stubble in no-till fields to pre-fire levels. The organic matter in the burned wheat stubble will likely impact fertility levels and affect the amount of fertilizer producers apply. But that won’t prevent the fields from being planted next season.

Last year, Oregon harvested 690,000 acres of winter wheat. Just before the Substation Fire erupted, the U.S.D.A. forecast an increase for 2018 to 710,000 acres. Oregon winter wheat yielded 63 bus per acre in 2017, the U.S.D.A. said, and it forecast a decrease in 2018 to 54 bus an acre.

Governor Kate Brown of Oregon declared a statewide emergency on July 18 and wrote a letter to U.S. Department of Agriculture Secretary Sonny Perdue requesting emergency aid for farmers affected by wildfires, noting “This type of fire has not been seen in decades and has done untold economic damage to Oregon’s farmers.”

The letter, written in collaboration with Oregon Senators Ron Wyden and Jeff Merkley continued: “Our concern is that federal programs such as crop insurance, or even normal disaster assistance, are not sufficient for this type of disaster.”