For many people, Thanksgiving means loading up the car and hitting the road to visit family and friends.

And this holiday weekend that means contending with heavy traffic and stormy weather, including snow on the mountain passes.

Interstate 90 should be very busy Wednesday, especially around midafternoon, according to the state Department of Transportation.

“There’s going to be a lot of people on the roadway, and there’s going to be some severe weather at times,” Mike Westbay, a DOT spokesman, said.

Snow is expected in the mountain passes Wednesday, Thursday and Sunday, while the Yakima Valley should see intermittent rain and mild temperatures with highs in the 40s. Thanksgiving Day is expected to be dry in the Valley.

Motorists can also expect plenty of traffic. Wednesday is the busiest travel day of the year, according to AAA.

An estimated 43.6 million Americans are traveling 50 miles or more from home this week, a slight increase over last year’s 43.3 million, according to the auto club.

About 14.3 percent of the population — or 7.3 million people — on the West Coast and in Alaska and Hawaii are expected to be traveling. Most of those people — 6.3 million — will be driving.

The number of travelers has climbed steadily since 2008. But while there will be more travelers than last year, they aren’t going as far: 588 miles this year compared with 706 last year, according to the travel group.

They are expected to spend a median amount of $498 per trip, down from $554 last year, according to AAA.

Lower gasoline prices and air fares are helping that decline in spending, according to the group.

The average price of a gallon of gasoline is currently $3.52 in Washington, down 20 cents from this time last year, said Jennifer Cook, a spokeswoman for AAA.

Air fares are also down 11 percent this year compared to 2011, according to AAA.

Wednesday and Sunday are expected to be the busiest travel days, according to a survey for AAA and traffic forecasts by the DOT. Forty-five percent of the respondents to an AAA survey said they plan to depart on Wednesday, with 36 percent planning to return on Sunday.

Travel around Thanksgiving Day can be dangerous. Last year, 2,169 collisions occurred in Washington during the week around the holiday, compared to 1,901 collisions during the average week for the year, according to DOT data.

While car crashes are caused by many factors, weather can play a role.

“In winter conditions people have to change the way they drive,” Westbay said. “They can’t put it on cruise control and do 70 over the pass.”

Drivers crossing the Cascade Mountains need to plan ahead, allow more travel time, check driving conditions, have a full tank of gas and bring approved traction devices like chains, he said.