Barring last-minute intervention by President Donald Trump, tariffs will kick in on Sunday that could make future Labor Day celebrations a lot pricier — even if you never leave the backyard.

Included in the tranche of $300 billion worth of Chinese imports on which the White House is levying a 15 percent tariff starting Sept. 1 are a large number of consumer goods, and trade experts say it’s inevitable that American consumers will feel the pinch of higher prices. So far, companies have mostly absorbed the higher costs of higher parts and materials, but they have much less leeway to do so with tariffs on finished goods.

The tariff level had been set at 10 percent until Trump ordered it hiked by an additional five percentage points last week. The U.S. business community has strenuously objected, but the White House has given no indication that it plans to back down.

The Americans for Free Trade Coalition, a group made up of more than 150 business groups, has said the tariffs “could represent one of the largest tax increases in American history.”

On Wednesday, the group sent an open letter to the president, warning, “These new tariffs will act as a tax on U.S. manufacturers and U.S. farmers… The full adverse impact of these tariff increases will be felt entirely in the United States,” it said.

In real terms, this means a lot of everyday goods we enjoy during a carefree summer will get more expensive. Picnic essentials like plastic plates, bowls and serving trays, along with wood-handled barbecue tools, are on the tariff list published by the Office of the U.S. Trade Representative.

Americans have already been exposed to higher prices for some summertime activities: Tariffs on imported steel and aluminum, as well as on Chinese-made components, have made grills and grilling equipment more expensive.

Cracking open a cold one? That aluminum tariff has already made canned beer pricier, according to the Beer Institute. Manufacturers are paying nearly $350 million more a year because of the tariffs, the trade group says — costs that trickle down to your cooler. (Insulated cooler bags were hit in the last round of tariffs.)

And prices will keep climbing; the USTR confirmed that the previous tranche of tariffs, which had already been hiked to 25 percent from 10 percent in May, will go up to 30 percent on Oct. 1.

“We are just starting to see the impact of the increase from 10 to 25 percent, and the impact on consumers will continue to grow with this next round,” said Bethany Aronhalt, a spokesperson for the National Retail Federation. “We are reaching a tipping point in this trade war where American families will start to feel a greater impact as prices rise for a wide range of consumer products,” she said.

Economists have warned that retailers and businesses in other sectors could pull back on hiring or even cut jobs in order to make up for the revenue lost to tariffs, a concern echoed by Aronhalt. “Higher costs and business uncertainty will undermine U.S. economic growth and jeopardize American jobs,” she said.

The new round of tariffs "could represent one of the largest tax increases in American history,” said one business group.

Picnics and barbecues aren’t the only summertime activities targeted in the new tariffs that kick in September 1. From fishing rods to flip-flops, the USTR list covers a wide swath of items for which Americans will probably be surprised to find themselves paying more.

Hanging out in the yard? Toys ranging from soccer balls to sidewalk chalk to swings are getting hit with tariffs starting Sunday. Staying cool also will get pricier: Kiddie pools, water skis, surfboards and canoe paddles are all subject to the new tariffs, too. (Oh, and plan to drip-dry; beach towels are also on the list.)

Don’t count on a trip to your county or state fair to cheer you up: Carnival amusements like merry-go-rounds, shooting galleries and arcade games are also getting slapped with tariffs. The Popsicle stick for your corn dog? Yep, that too.