average temperature in houston in December
7 Â°C. In most years, Houston averages a daily maximum temperature for December that's between 61 and 68 degrees Fahrenheit (16 to 20 degrees Celsius). The minimum temperature usually falls between 41 and 49 Â°F (5 to 9 Â°C). The days at Houston continue to cool during December.early every December day warms to over 50 Â°F (10 Â°C) in Houston. The city averages 11 days this month when the thermometer reaches into the 70s Â°F (over 21 Â°C). One or two days in December can even get as warm as 80 Â°F (27 Â°C).