Average Low (°C)          || Record Low (°C)
             | Dec  | Jan  | Feb  | Mar  || Dec   | Jan   | Feb   | Mar
    Oslo     | -3.9 | -4.7 | -4.7 | -2.1 || -19.7 | -20.5 | -20.7 | -16.9
    Toronto  | -3.1 | -6.7 | -5.6 | -1.9 || -30.0 | -32.8 | -31.7 | -26.7

The winter in Oslo starts earlier and lasts longer... but isn't as extreme as Toronto's winter.

The record low for Feb in Oslo (1991 - 2020 data) is -5.3°F. That's an average winter night for me. https://www.aos.wisc.edu/~sco/clim-history/stations/msn/msn-...

Another way of looking at this... heating degree days.

https://www.weatherbase.com/weather/weatherall-print.php3?s=... vs https://www.weatherbase.com/weather/weatherall-print.php3?s=...

Oslo has 6286.8 heating degree days. Toronto, Ontario has 7342.8.

Toronto is substantially colder than Oslo (edit...) when it comes to the extremes of weather.

(edit: correction) - Oslo's is https://www.weatherbase.com/weather/weatherall.php3?s=88410&...

which has the heating degree days as 7787.8 which is now comparable to Toronto.