I wrote the following 2 years ago in response to a question from my 3rd cousin who was raised in South Africa and is now living in Western Australia. His wife had purchased some patterns made in Canada and was surprised to find them measured in inches. So he asked me if we still used the old inches, feet and yards system. He also asked if we used Fahrenheit or Celsius for temperature. This was my reply:
Just as Canada is officially bilingual (English and French) though few outside Quebec are fluent in both, we are unofficially bimetric (I just made up that word).
Canada half-heartedly made the official switch to metric about 30 years ago but we never completely let go of the old system. I think they even still use inches and pounds in grade school. For decades we have had both systems overlapping. The intention was for the confusion to last for just 1 generation but we haven't been disciplined enough to learn the new system well enough to let go of the old, which just prolongs the agony.
We think of distance in either miles or kilometers. Both work efficiently for different distances -- for short distances miles approximates minutes of travel at 60 miles per hour (e.g. 35 miles will take 35 minutes) while for longer distances 100 km approximates hours and fractions thereof at 100 km per hour (e.g. 250 km is 2.5 hours). Metric fuel consumption never caught on at all - only in auto ads do you hear liters per 100km; everyone on the street still thinks in miles per gallon (20 used to be standard, newer efficient cars can brag 35-40 mpg). Gasoline pumps did switch to litres years ago just as the price reached $1 per gallon, so they could list it as $.22 (or whatever it was then) instead. However over the years the price of gas has climbed until it surpassed the $1.00 per L mark (and was heading for $2 before the recession brought it back below $1 again).
Grocers sell produce with the price listed "per 100g" but also list in small print the "per pound" price; fabric stores will measure centimeters or inches, whatever the customer asks for, and calculate the price accordingly. Older patterns would be in inches; more recent ones (unless from the USA) in cm. Grain is sold officially by the tonne (1000kg) but the price of grain is still discussed among farmers as $/bushel, or yield as bushels per acre instead of the official tonnes per hectare. Few farmers here could tell you how big a hectare is but they all know what an acre is. For one thing the land in western Canada was surveyed into 160 acre Quarter Sections (a Section is 1 mile x 1 mile so a Quarter Section is 1/2 mile x 1/2 mile), so for that reason it still makes some sense to work land area in acres and sections.
The other reason for the resistance to change is our biggest trading partner and neighbor to the south - the USA. They do not have a strong enough government to enforce a switch - the people wouldn't stand for it. Besides they think they are important enough that everyone else who wants to do business with them can speak their language including their measurement system. Products imported into Canada from the USA have some interesting measurements like 946ml (USA 32 oz or 1 quart) or 454g (USA 1 pound). It's easier to just use the American bottle and change the label.
To return to your first question, temperature is a little better than half converted. The weather reports all use C but some people still talk in F. Thermostats can be set to read either and most thermometers have both, one on each side of the red line. Everyone knows the significant temps in both systems - water freezes at 32F or 0C; comfortable room temperatures is 70F or 20C; and -40 is just as cold in both!
There, ended up writing an essay to answer a simple question.