Weather can make or break a road trip, so here's some data about year-round temperatures in Sydney Mines to help you plan yours: The hottest months are usually August and July, with an average temperature of 16°C, while the coldest months are February and January, with an average of -2°C. The snowiest months in Sydney Mines are February, April, January and December, with each month seeing an average of 217 cm of snowfall.