With expected storms, snowfall, delayed flights and labor action in what could be the busiest holiday travel season ever, Americans hit the road this week with the hope rather than the expectation of hassle-free travel.

Two major storm systems could cause travel chaos across much of the country, bringing rain and snow to communities and major cities. Since Friday, 17,000 flights across the country have been canceled or delayed due to severe weather.

Flight tracker FlightAware recorded 3,760 delays and 60 cancellations as of Monday evening, with San Francisco the hardest-hit transportation hub. These numbers include travel to and from the United States. Significantly further disruptions are expected throughout the week.

Making matters even more difficult for some, service workers at Charlotte Douglas International Airport in North Carolina walked off the job at 5 a.m. Monday after voting to strike on Friday. The Service Employees International Union (SEIU) said it plans to “end poverty wages” and demand “respect in the workplace during the holiday travel season.”

The striking workers are ABM and Prospect Airport Services employees whose duties include cleaning aircraft and caring for passengers in wheelchairs. The workers there also went on strike in May.

The airport’s online departure display initially showed no effects of the strike. Charlotte Douglas is the ninth busiest airport in the United States and handled more than 25 million passengers last year.

Later Monday, a few dozen SEIU workers at Los Angeles International Airport, some carrying signs reading “Airport workers will close it,” demonstrated for better pay and access to affordable health care, potentially causing travel delays on the West Coast. The union is calling for an increase in the minimum wage from $25 to $30 an hour.

Millions of travelers are already stressed

Traveler Marc Supreme took 12 hours to get from Peoria, Illinois, to Atlanta on Thursday due to ice and snow, and he says it worries him that the week could bring more bad weather in the Midwest.

“That’s true, especially because I didn’t even know the weather was prevailing. I should have checked so I think it’s one of the things for the holidays. Make sure you check the weather because I had no idea I was going.” “It takes me 12 hours to get to Atlanta,” he said while arriving at the Hartsfield-Jackson Atlanta International on the way back to Illinois Airport was waiting.

College student Emma Welch flew to Atlanta on Sunday from Chicago, where she is studying law, and said she was somewhat concerned about possible travel issues due to upcoming exams.

“A little bit, just because of finals and stuff, but hopefully everything will be okay,” she said. When she booked her return flight, she said she didn’t realize Sunday would be one of the busiest travel days of the year. Instead of showing up three hours early to avoid complications, she instead shows up with four hours to spare.

Around 80 million people are expected to travel by road, rail, air and even cruise ships this week, traveling more than 50 miles from home between Tuesday and next Monday.

“This will be the busiest Thanksgiving ever in terms of air travel,” TSA Administrator David Pekoske said on

A later-than-usual Thanksgiving — the last Thursday of this year falls on Nov. 28 — could lead to greater travel pressure next Monday and Tuesday as more people head home rather than extending their visits.

Many are heading south, with the main airports of Orlando and Miami each expecting 1.9 million travelers to transit during the 12-day travel period.

Weather problems are affecting holiday plans

NBC meteorologist Michelle Grossman said two separate storm systems would bring bad weather to different parts of the country. Strong winds and snow could occur in the Rocky Mountains and Cascades on Monday and Tuesday, making travel in mountainous areas difficult. Up to 5 inches of snow could land in Michigan’s Upper Peninsula, with other areas likely to see between 1 and 5 inches.

This weather system will then shift eastward, causing potential problems on roads with up to an inch of rain from southeast to northeast – although the afternoon could be drier. On Wednesday, this storm will strengthen and expand, bringing a wintry mix of rain, snow and strong winds.

Thanksgiving will be a rainy day across much of the East Coast, from New England to the South, while it could be bitterly cold in northern states and reach 26 degrees in Minnesota.

The second storm system is expected to impact from California to New England, causing widespread heavy rain and snow across the mountain ranges. On Monday, the Pacific Northwest could see between 1 and 3 inches of rain and 3 to 4 feet of snow in the highest parts of the southern Sierra Nevada.

Best time to travel?

The vast majority of trips this Thanksgiving will take place on the road, with 71.7 million car trips exceeding last year’s figure by 1.3 million – thanks in large part to lower gas prices, which could hit a national average of $3 a gallon this week .

Data from traffic analyst INRIX shows Tuesday and Wednesday afternoons will be the busiest times on the roads. But people may not realize that Thanksgiving Day itself is “usually clear.”

“We recommend leaving early in the morning (on) Tuesday and Wednesday, the afternoon hours are the worst,” AAA spokeswoman Aixa Diaz told NBC News.

“We always say that traveling on the holiday itself is the best day to travel, not only because you get cheaper tickets by plane, but also because there are simply fewer people on the roads and at the airports,” she said.

This article was originally published on NBCNews.com