Many Americans first became familiar with the term ‘polar vortex’ in the winter of 2014, when the north polar vortex – normally confined to the Arctic – drifted south through Canada and into the continental US, affecting millions of people and creating record-breaking temperature lows.

The polar vortex swept down from the Arctic Circle again in the last few days of January this year, causing the deaths of at least 22 people and wreaking havoc on infrastructure and services across the US Midwest and Northeast. Airports were hit hard by the deluge of snow, ice and some of the lowest temperatures ever recorded in the country. Thousands of flights were delayed or cancelled as airport operators struggled to keep up with schedules amid the epic challenge of de-icing planes, taxiways and runways.

Below are profiles of some of the most important air hubs impacted by the winter woes of January 2019, and the actions taken to prepare for the coming storm.

Chicago O’Hare/Chicago Midway, Illinois

The city of Chicago bore the brunt of the polar vortex, with local temperatures plummeting as low as -31°C – the coldest recorded since the all-time record of nearly -33°C in January 1985 – at the city’s two main airports, O’Hare and Midway. At Midway, over 40% of the airport’s planned flight schedule was cancelled (237 flights) on Thursday 31 January, while around 1,400 departures and arrivals were cancelled at O’Hare, more than half of the daily schedule.

As a hub airport for United Airlines and American Airlines and a major nexus for domestic flight transfers, the problems at O’Hare were particularly damaging, as cancellations rippled out to affect hundreds of flights from other airports across the country.

Detroit Metropolitan Airport, Michigan

In Michigan, Detroit Metropolitan Airport was closed for a full 14 hours by the arctic conditions. The airport was shut down between the evening of Tuesday 29 January and mid-morning the following day. Airfield maintenance crews had been hard at work to treat the runway and taxiway, but the weather conditions hampered their efforts.

“For several hours prior [to the airport’s closure], maintenance crews actively treated the airfield,” said a Detroit Airport spokesperson in a statement. “However, the constant rate of precipitation has diluted the de-icing fluid, causing it to be ineffective.”

Atlanta Hartsfield-Jackson Airport, Georgia

It wasn’t just the Midwest and Northeastern US that were impacted by the polar vortex; freezing temperatures extended as far south as Louisiana and Alabama. In Georgia, Atlanta’s all-important Hartsfield-Jackson International Airport had hundreds of flights cancelled as the city prepared to host the Super Bowl, the National Football League’s championship game.

The airport prepared for the storm by stocking up on nearly 80,000 gallons of pre-treatment fluid for runways and taxiways, and more than 50 tonnes of ice-breaking pellets. As well as the cumulative delays racked up by the constant need for de-icing of planes and airfield surfaces, extreme low temperatures also pose dangers to airfield staff such as baggage handlers and maintenance crews, who need to seek shelter more often to minimise exposure.

“When you get below 35°F, everything starts slowing down,” said Aviation Management Consulting Group managing principal Jeff Kohlman in a January interview with Wired.

Mitchell International Airport, Wisconsin

No stranger to the need for snow preparation is Mitchell International Airport in Milwaukee, Wisconsin, one of the three states – along with Michigan and Illinois – to declare states of emergency over the snowstorm.

While delays and cancellations did affect the airport, it was able to remain open through the storm thanks to the well-trained efforts of airfield crews, which operated on 12-hour shifts to ensure that rested workers were available night and day. The airport’s 12 snow plows can clear its runway and taxiways in around 20 minutes; Federal Aviation Administration regulations require runways to be cleared if more than one inch of snow builds up.

“There’s a certain pride in what we do here, and it’s knowing that without us…having these skill sets, the airfield would be lost without us,” airport maintenance worker Ashley Koehlert told WISN Milwaukee.

Denver International Airport, Colorado

While Denver International Airport in Colorado was left relatively unscathed by the polar vortex in late January and early February, over March and April it has been battered by another type of winter storm that Americans are becoming increasingly familiar with, and which has a similarly colourful description: the ‘bomb cyclone’.

These weather patterns, caused by the deepening of cyclonic low-pressure areas, caused the closure of all runways at Denver International on 13 March – for only the fourth time in history, according to the Denver Post – as 96mph winds and whiteout conditions grounded flights and made it too hazardous for snow plows to operate.