Olyokminsk has a
subarctic climate (
Köppen climate classification Dfc). Winters have temperatures averaging from in January, while summers have average temperatures from in July. In the summer months of June, July, and August, it is not uncommon for temperatures to surpass during the day.
Precipitation is significantly higher in summer than at other times of the year. Although summers are similar to republic capital
Yakutsk, winters are less severe courtesy of the lower latitude. As a result, Olyokminsk is rare for the Sakha Republic cities in that it has recorded above-freezing temperatures during January and February. Those episodes are rare and very short-lived. On August 6, 1986, Olyokminsk recorded its highest ever temperature of . The record low for Olyokminsk was in 1907. July is the only month when temperatures never dropped below and December is only month when temperatures have never reached . ==References==