Cold weather is defined according to ACI PRC-306-16 Guide to Cold Weather Concreting as “a period when the average daily ambient temperature is below (or expected to fall below) 40°F (5°C) for more than 3 successive days”
The average daily ambient temperature is the average of the maximum and minimum temperatures during a day measured from 12 AM to 12 AM. If the average in a day exceeded 5°C, we do not consider this a cold weather.