The SAE seems to define a temperature below -10 °C as "cold".
Viscosity ratings for motor oils to be used in cold weather typically range from 0W to 25W ( the W stands for "Winter" grade).
The numbers refer to the viscosity of the oil at designated temperatures.
Effectively, you can subtract 35 from the numerical rating to get the designated temperature range for the oil.
Thus, 25W oil has defined viscosities at -10 °C and -15 °C.
0W oil has defined viscosities at -35 °C and -40 °C.