Average Temperature Outlook for CLE ELUM (issued in February 2017) suggests that during Mar-Apr-May 2017:

There is a 99% chance that the average 3-month temperature will be within the range of 41.4 and 49.6 Deg F,.

There is an approximately equal ( 49.0%) chance that the temperature will be higher than the climatological median* of 45.5 Deg F, and an approximately equal (51.0%) 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.