An online system predicts whether a location will experience a threshold increase in traffic over the location's historical average amount of traffic. To predict a future deviation over historical traffic, the online system identifies events within a threshold distance of the location and determines an average number of indications that users will attend events within a threshold radius of the location during a prior time interval. The online system determines a total number of indications that users will attend future events within the threshold distance of the location, disregarding locations associated with less than a threshold number of future events and future events for which the online system received less than a threshold number of indications that users will attend, and determines a ratio of the total number of indications to the average number of indications that users will attend received for the prior events during the time interval.