On a cold December day, food trucks attract few customers during their normally busy lunch hour in downtown Washington. (Jahi Chikwendiu/The Washington Post)

Spring, summer and fall, Nevan William gets about 80 customers a day when she parks her kebab truck on Franklin Square. On the first day of winter, she got 18.

Before packing up and pulling away a half-hour early last week, she had made enough to pay an in-truck helper her $90 salary and to cover about half of the $300 in lamb and chicken and gyro meat she had bought that morning.

Such is the equinox in Washington’s lively food truck scene, which blooms for three seasons and can dangle like a twig in the darkest months.

“When the cold comes, they leave us out here alone,” William said, leaning out of the window of Kabab Village and scanning the empty sidewalk.

For food trucks, winter is the season of their disconnect. The long lines of hungry lunch seekers are daunted by the chill wind, leaving mobile chefs to stew with their stew, all but alone with the gumbos, tacos and bibimbap.

Nevan William waits for customers at her Kabob Village food truck, parked near Metro Center, (Jahi Chikwendiu/The Washington Post)

Truck owners report typical revenue drops of 50 percent or more during the cold months, with some days dwindling to a just a sale or two when the weather is wintriest. It’s a chilling — sometimes killing — season for microbusinesses that may have jumped in during the summer only to be caught unprepared when January sends the numbers over the cliff.

“It surprises a lot of vendors, which surprises me,” said Najiba Hlemi, executive director of the DMV Food Truck Association, which represents an industry where many entrants are entrepreneurs or foodies from warmer climates. “We stress to people coming in that seasonality is a huge component here in a way that’s true not in Florida or California and some other places where the food truck trend is big.”

Her group sees its membership drop about 20 percent each winter, reflecting a huge seasonal die-off within a fragile marketplace. “Some of them go dormant, but some of them go out of business completely.”

A third or more of the 404 licensed D.C. food trucks just put their mobile business in park for the season, Hlemi said. It’s a good time to work on the menu and fix up the truck. But many just slog through, buying less and selling less and waiting for the cherry blossoms to bring more life to lunchtime.

William’s routine is the same but the results are smaller. She leaves her house in Northern Virginia at 5 a.m. for a supply run to Restaurant Depot. She chops her ingredients in the Washington garage where she parks her pyramid-emblazoned truck. At 9:30, she drives to her lottery-assigned spot for the day, parks and begins to cook. By 10:30, the early-bird lunchers show up, at least when it’s warm.

“All the work is the same, but not so many people come,” she said. She would use the slow stretch to update her rolling kitchen, which could use about $5,000 in work. But the reality of winter is a cruel paradox: “Now we have time to do it, but we don’t have the money.”

John Rider is a veteran of 20 D.C. winters as a sidewalk chef. Most days, the owner of Pedro and Vinny’s Fresh Burritos at the corner of K and 15th streets just slashes his inventory and takes his 50 percent revenue cut. But even he will wave the white tortilla when lunch is truly a lost cause.

Many of the food trucks that park on Franklin Square have to get by in winter with at least 50 percent less revenue. (Jahi Chikwendiu/The Washington Post)

“If anything falls out of the sky on a winter day, I don’t come,” he said. Now, at least, he can use Twitter, foodtruckfiesta.com and other tracking apps to let his followers know when not to brave a blizzard in pursuit of a burrito.

Cecil Boyd grew up with D.C. winters, but this is the first he’s trying to navigate as a food truck owner. He and his family rolled out the Seafood Boss this year and he’s bracing for a dip that became noticeable with the first blustery day in December. He has tweaked his menu of fried fish and shrimp to include crab bisque and lobster macaroni.

“I haven’t been through it before but we’re trying to be ready,” said Boyd, who was parked last week in NoMa.

To ease the seasonal crush, Hlemi’s group has started working with local banks and nonprofit lenders to provide winter bridge loans for those who may need a little boost to reach the spring. They encourage their members to use Uber Eats and other services to provide delivery, and are developing an app to let customers order in advance for pickup from nearby trucks.

“A lot of people still want to get up from their desks and get outside in the winter; they just don’t want to be outside for a long time,” she said.

The proprietors of the BBQ Bus, a popular wheeled meatery since 2011, decided to close entirely after Thanksgiving and rely on holiday catering to see them through. Weather depending, they will take up their curbside stations after the despond of January (a month of desperate dieting and strained credit cards) has passed.

“We have regulars,” said co-owner Che Ruddell-Tabisola. “We don’t want to stay out of sight for too long.”

Kirk Francis would seem more at risk than most to winter’s bite. His three Captain Cookie and the Milkman trucks pump out an ice cream-heavy menu of treats and, although he may see a bump around Valentine’s Day, winter is a long trough.

He gets through by taking one staffer off each truck and putting them to work on a growing sideline of “indoor catering” office parties and special events where he deploys a cookie table and a new ice cream cart. It’s also research and development time. Last winter they perfected an edible cookie dough now on the menu. This year they’re seeking a make-in-advance ice cream sandwich that stays soft while frozen.

“In the summer, it’s too frantic to do much but meet demand,” he said.

Francis said he never considers pulling his trucks. For one thing, he has customers who will brave any weather for a chocolate chip fix. For another, he sees year-round value in having his gaudy logo forever in his city’s face.

“Whatever business they’re doing,” he said, “these trucks are giant billboards.”