If you're planning on taking GO Transit or the UP Express in the coming weeks, you may have to make some last-minute alternative travel arrangements, as Metrolinx has issued a warning to passengers that there are some "possible cancellations" on the way as they deal with staffing shortages.

A PSA on the agency's website states that "staff illnesses" are the reason behind forthcoming trip cancellations, and that customers should plan ahead, allot extra time and check online first to see if their route is still running.

An advisory on the GO Transit website tells passengers that there are some train cancellations on tap this week due to operators testing positive for COVID-19.

A spokesperson for Metrolinx told blogTO these changes will amount to "minor adjustments" and that train cancellations will only be "isolated and temporary" over the next two weeks, adding that they will be giving as much advance notice to customers as possible.

"We continue to work with Alstom, our train operator who has been recruiting and training, and as more crews become available, we will continue to incrementally add more service," they added.

At the time of publication, among the list of 13 current train and bus disruptions on the GO website, there was only one full cancellation due to lack of available operators: the 3:34 p.m. Union Station to Kitchener train.

We are sorry to advise that due to staff illnesses we will need to cancel some trips this week. Please check the Service Alerts page before travelling, https://t.co/gVBd9UIinT. Always check the departure boards at your station before boarding.

— UP Express (@UPexpress) August 7, 2022

While the UP Express is running as usual on Monday, the Twitter account for the airport train stated on Sunday morning that there would be a longer wait between trips due to staff illness.

The team also advised that there will be future cancellations of "some trips" this week, though it is not yet known which date and times on the usual schedule will be impacted.

More, larger interruptions may be ahead, though, as in addition to these staffing issues, GO Transit is facing a looming strike by the union representing its bus operators, station staff and safety officers, maintenance workers and more if a new deal is not reached.