Temperatures have already fallen to -35C at the Winnipeg airport as of 8 pm this evening.. and with clear skies and a light northwest flow, conditions are favourable for the airport site to drop to the -40C mark overnight. Note however that temperatures in the city are several degrees "warmer" as of 8 pm this evening, ranging from -27 at the Forks to -30 in the outskirts. You will notice that the Winnipeg airport site can get quite a bit colder at night than the rest of the city in a light northwest flow and clear skies. The weather station at the airport is located in a remote field on the northwest side of the airport, which seems to get some dramatic cold air drainage or radiative cooling in a light northwest flow. In these cases, the temperature at the Winnipeg airport is not very representative of the temperature elsewhere in the city.. which are often some 5 degrees "warmer" than the airport. This can easily be seen when looking at a Google map of city temperatures.
Regardless.. whether it's -35 or -40.. it's going to be a bitterly cold night!