It’s the Fourth of July weekend! Happy 250th to the Grand Old Republic!

May the heat spreading across much of the United States not get to you too much.

And one more thing: Enjoy lower gas prices. Maybe not as low as the $2.50 a gallon President Trump was demanding this week — along with a price-gouging probe of oil companies.

But gasoline prices at $3.79 per gallon nationally are 17% lower than at their peaks on May 6 and May 20, according to GasBuddy data. And prices are more than 15% lower than the national average seen on Memorial Day weekend, when prices averaged $4.49 a gallon. But, it must be added, prices are still up 34% for the year.

The bottom line for drivers: The cost of a 15-gallon fill-up has dropped from $68.49 (at $4.67 a gallon) to $56.85 (at $4.49), a savings of $11.64.

I wrote a story earlier this week noting the savings might buy you a Big Mac, fries and a drink.

Prices should drift lower at least through the weekend, Patrick DeHaan, GasBuddy’s head of Petroleum Analysis, told TheStreet. “It’s not a bad week for the holidays,” he added.

If there is one immediate issue, it will be the heat dome settling over the eastern half of the country with temperatures approaching 100 degrees and high humidity. (New York City was seeing temperatures above 90 degrees Fahrenheit on July 1, with a forecast of 100 degrees or more on July 2.)

Millions “will be at risk of either ‘major’ or ‘extreme’ heat-related health issues,” the National Weather Service’s HeatRisk tool said. That may make filling up a gas tank an uncomfortable experience.

If you’re going to . . .

The prices you will see over the weekend will reflect regional and national trends.

Prices will be highest on the West Coast and in many western states, reflecting higher taxes, distribution costs, and charges to try to mitigate environmental concerns. Drivers in California, Hawaii, and Washington will face prices above $5 a gallon.

Mono County in rural eastern California has the highest prices, averaging $6.476 a gallon. That reflects the costs of transporting gasoline through the Sierra Nevada mountains to the stations. Neighboring Inyo County has the second-highest price, at about $6.019.

San Francisco has the highest average in urban areas at $5.628 per gallon.

Drivers in the deep South and some midwestern states have the lowest prices.

The lowest prices will be found in Indiana, Oklahoma and Texas, all below $3.30 per gallon.

What it will cost in places you visit

I was interested to see what prices in locales people might be visiting for fun this weekend and in July, as the summer driving season typically hits its peak.

Prices reflect regional realities and how hard it is to get the gas to the gas station.

Gasoline in Park County, Wyo., home to Yellowstone National Park, are averaging about $4.13. Temperatures at the nation’s oldest national park will be in the 70s all weekend, Weather.com says. And nights will be in the 40s.

Visitors watching Old Faithful geyser erupt in Yellowstone National Park.

Mario Tama / Getty Images

A gallon of gas in Honolulu will run you $5.43 a gallon, maybe less. A relative bargain compared with San Francisco.

In Sevier County, Tenn., by the entrance to Great Smoky Mountain National Park, prices are around $3.21 a gallon. Tennessee is a low-cost state.

Heading to Martha’s Vineyard, off the coast of Massachusetts? You’ll probably pay $3.90 a gallon. Fuel has to be shipped by commercial freight ferries or special tank barges.

In Orlando, Fla., look for gas at about $3.82 a gallon. And a heat warning.

The risks ahead

Once we get past the weekend, there are risks to the current gas-price picture, GasBuddy’s DeHaan said.

The tensions in the Middle East have not abated. President Trump, in fact, has been weighing “a return to all-out war” with Iran, The Wall Street Journal reported on July 1. A renewal of the war would certainly push gas prices higher.

For now, at least, he has decided to stick with diplomatic efforts to negotiate a peace with Iran, the Journal said.

The U.S. efforts are focusing on getting the Strait of Hormuz open. Iran wants to control it and charge ships millions of dollars to pass through.

A second issue is a bit of a surprise. But GasBuddy’s DeHaan said that Russia is experiencing worsening gas shortages, the result of successful Ukrainian missile and drone attacks on Russian oil refineries. Some are even located on the outskirts of Moscow. The situation is so serious, said oil trader John Kilduff, that Russia has to import some of its gasoline, said oil trader John Kilduff in an interview.

One last question: Can the President order oil companies to cut gas prices to $2.50? Not really, DeHaan said. Besides, the oil in a gallon of gasoline is maybe 57% of the price.

But all that is geopolitics and politics, and this is a special weekend, regardless of your political outlook.

So, have fun in the heat. Or not. (A friend suffering in New Hampshire was looking forward to a weekend near the Atlantic Ocean.)

Related: U.S. car sales take unexpected turn in tumultuous first half