The Fahrenheit temperature is double the Celsius temperature at the point where the two temperature scales intersect. This point is at -40 degrees, where -40 degrees Fahrenheit (-40 °F) is equivalent to -40 degrees Celsius (-40 °C). At this temperature, the numerical values on both the Fahrenheit and Celsius scales are the same, making it the only temperature where the Fahrenheit reading is exactly double the Celsius reading. Therefore, -40 °F is the temperature where Fahrenheit and Celsius temperatures are numerically equivalent, representing the point where the Fahrenheit temperature is double the Celsius temperature. This particular temperature holds a unique significance as the only point where the relationship between the Fahrenheit and Celsius scales results in a doubling of temperature values.