As thick fog rolled into Toronto on Wednesday evening, chaos ensued at Pearson Airport.

Just before 8:30 p.m. last night, the airport tweeted that, in order to maintain safe operations amid the fog, NAV Canada had reduced the flow of arriving aircraft. Pearson warned that flights may be delayed as a result.

My sister, flying into Pearson last night with the heavy fog! 🫣✈️ #yyz pic.twitter.com/WY9rn5klPA

— Leanne リアン (@leannes) November 3, 2022

According to data from FlightAware, 177 departing flights and 172 inbound flights were delayed at Pearson on Wednesday; the latter figure was the highest of any airport in the world yesterday.

Some incoming flights were diverted to airports in other cities, including Ottawa and Montreal.

PHOTO Several holding patterns at Toronto Pearson this evening. Low visibility, thick fog- 1/4SM with 100ft of vertical visibility. Few diversions away already taking place. pic.twitter.com/tAOvYmIlix

— Ernest Gutschik Aviation (@ErnestGutschik) November 2, 2022

Conditions - both weather and transportation related - had not improved by daybreak Thursday.

Environment Canada issued a fog advisory for Toronto and Mississauga this morning, warning that visibility may be "significantly and suddenly reduced to near zero." Travel is expected to be "hazardous" as a result.

Dense fog currently covering Pearson CYYZ ! Air mess, many eastbound flights diverting to YWG and westboun diverting to YOW/YUL #torontopearson #yyz pic.twitter.com/Mx0o31iZsx

— Marcos Oliveira 📸🗞️ (@AeroMarcos320) November 3, 2022

While the fog is expected to dissipate later this morning, delays were still plaguing Pearson.

The airport took to social media to warn travellers that operations may be impacted, and advised that they check their flight status ahead of time.

Regional weather may impact operations this morning at Toronto Pearson. Please check your flight status with your airline before leaving for the airport.

— Toronto Pearson (@TorontoPearson) November 3, 2022

As of 11:00 a.m., Pearson has already delayed 51 outbound flights, and cancelled 24. Eighty-four incoming flights have been delayed thus far while 25 have been cancelled outright.