Commuters across the GTA are facing another round of transit disruptions Thursday as extremely cold weather maintains a grip on southern Ontario.

Service to and from Pearson International Airport was the first to go.

The UP Express was suspended on Wednesday night due to issues caused by the extreme cold. Though service did briefly resume on Thursday morning, it was halted again by 8 a.m. for the same issues.

Trains started moving again at 12:30 p.m., but were running every 30 minutes instead of every 15.

Trains will stop running again at 9 p.m. tonight due to weather-related problems, the service said Thursday night. Buses will be running between Union and Pearson and between Weston and Pearson instead.

Metrolinx spokesperson Matt Llewellyn said the "fine, sugary snow" on the ground is to blame for the issues.

"It seems to get into every crease and crack into the actual UP unit and when it is whipped up by the wind, that's when it really creates problems," Llewellyn said.

"We just want our customers to know that our crews are working around the clock to ensure our trains continue to operate safely in these extreme weather conditions."

Llewellyn called the UP Express trains the “workhorses of the Metrolinx fleet” and said they will require an extended period of time to properly thaw out before returning to a full service schedule.

In the meantime, he encouraged UP customers to use GO Transit or the TTC to get to work.

But service on parts of the TTC is not faring much better.

For the fourth consecutive day, trains are not running on the Scarborough RT.

Train service was shut down on Line 3 shortly before the evening commute on Monday when a record-breaking snowfall slammed the city. Since then, mechanical issues and weather-related problems on the tracks have prevented crews from restoring service.

The TTC says high winds are causing snow to drift and build up along the rails.

“The challenge that we have is that, as quickly as crews can clear one part, another part has a drifting issue. So you get snow cleared from one area and then another section that you’ve just cleared may have snow build up,” TTC spokesperson Stuart Green said.

“It’s like trying to shovel your driveway when snow is falling very quickly.”

Shuttle buses are running along the route in the meantime, but riders aren’t happy.

“It’s miserable,” said one rider, who did not provide his name.

“I live up at Scarborough Town Centre and people will dogpile the next bus. The shuttle buses are inconsistent. Everybody is just trying to get to work or school… it’s a lot of stress.”

At Kennedy Station, a long line-up cars were idling as congestion from shuttle buses and kiss-and-ride users intensified.

A TTC supervisor told CP24 the traffic jam was the worst he’s ever seen at the station.

One driver said it typically takes her a few minutes to leave the station and get onto Kennedy Road, but today she waited more than 25 minutes.

“I’m not sure what’s happening here today but it’s awful,” one driver said. “The wait time to get my son to an exam and my daughter to school is just…. unbelievable.”

Toronto Mayor John Tory said the relentless issues with the RT highlight the increasing need for the now-underway Scarborough subway extension.

“This piece of technology, the SRT – if you can call it technology – it’s obsolete, it’s old fashioned and it’s breaking down because it’s old,” Tory said.

“I want to replace it as soon as possible with a subway and we’re getting on with building that subway. I don’t want people to hold us up because the people have spoken and they say the transit plan, including the Bloor-Danforth extension to Scarborough is the way to go, and that’s exactly what we’re doing.”

An extreme cold warning remains in effect today in Toronto, which saw wind chill values near -36 this morning. By afternoon, the temperature rose to a high of -15 C, feeling close to -27.

The weather is expected to improve over the weekend when milder air arrives.

But for some, this week’s weather-related delays has them rethinking public transit.

“I’m just trying to get to school. As soon as I finish this, I’m getting a car,” said one rider.

“I can’t handle it anymore.”