Average Temperature Outlook for CLE ELUM (issued in August 2016) suggests that during Sep-Oct-Nov 2016:

There is a 99% chance that the average 3-month temperature will be within the range of 42.0 and 51.2 Deg F,.

There is a greater ( 61.0%) chance that the temperature will be higher than the climatological median* of 46.6 Deg F, and a lesser (39.0%) chance that the temperature will be lower than the climatological median*.

*For the climatological reference information, the median statistic is reported. The median value means that during the present climatological reference period (1981-2010), half of the years (50%) temperature was greater than the median and in the other half (50%) less than that.