If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Gallup: The hottest months are usually July and June, with an average temperature of 21°C, while the coldest months are January and December, with an average of 1°C. The snowiest months in Gallup are January, February, November and March, with each month seeing an average of 17 cm of snowfall.