Heat problem on 2001 Ford Focus

When in park - heat full blast - there is heat - not alot but there is heat. When driving the temperature gauge drops right down and there is absolutely no heat. Coolant level is in the normal range. This is Fort McMurray and we have been in a cold snap - temperatures ranging from -34 to -18 celsius

1 answer
If the car is taking longer than it used to to 'warm-up' , then the thermostat may be opening to soon or stuck open.