If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Nikiski: The hottest months are usually July and August, with an average temperature of 12°C, while the coldest months are January and December, with an average of -5°C. The snowiest months in Nikiski are December, November, February and March, with each month seeing an average of 21 cm of snowfall.