If your travel plans were thwarted because of a flight delay or cancellation this year, you weren't alone.

The U.S. Department of Transportation said Thursday that among airlines' reporting figures, 71.8% of flights arriving in the U.S. in June were on time. That may seem high, but it's down from 76.9% the month before and 71.9% in June 2013. A flight counts as late if it arrives more than 14 minutes behind schedule.

The DOT says that, in the first half of 2014, the rate of late flights was the highest since 2008 and cancelations were the highest since 2000.

Extreme weather was a contributing factor, as cities in the central and eastern parts of the United States saw record low temperatures and snowfall. Chicago had its third coldest winter ever recorded, and ice covered parts of the Great Lakes through winter into spring.

A large winter storm hit the south at the end of January, creating transportation problems in cities usually safe from freezing temperatures like Atlanta and Birmingham.

As they often do, Hawaiian Airlines and Alaska Airlines had the best on-time ratings — the two regional airlines are the most protected from weather delays in the midwest and East Coast. Delta Air Lines had the best ratings among the biggest carriers.

Southwest and American were the worst of large carriers, while regional airlines Envoy and ExpressJet were also at the bottom, with more than 30% of flights arriving late.

About 2% of all flights in June were canceled, with Envoy, ExpressJet and SkyWest faring the worst. Delta, Hawaiian, Frontier, Virgin America and Alaska all had minuscule cancellation rates of 0.2% or lower.

For the January-to-June period, 3% of all flights were canceled, the third-worst performance in the last 20 years, according to the government figures.

See also: Score the Best Flight Deals on These 10 Sites

Jean Medina, a spokeswoman for Airlines for America, a trade group for the large carriers, said weather has been the biggest factor all year, with 17,370 weather-related cancelations in the first half of 2014 compared with 11,480 in the same period last year.

"With the exception of April, every single month had worse weather-related cancellations than the year earlier ... there were times it was simply not safe to fly," Medina said.

For the first six months of 2014, 74.2% of flights by the reporting airlines were on time. That is the fifth-lowest mark for the period in the last 20 years and the lowest since 2008 and 2007.

Consumers filed 1,095 complaints with the government against U.S. airlines, an increase of 16% over June 2013. Hawaiian, AirTran, Southwest and Alaska had the lowest rate of complaints, while Frontier, United and US Airways had the highest.

Additional reporting by the Associated Press