The forecast called for rain. Rain and clouds. Possibly snow, depending on elevation. The Siskiyou mountains aren't quite as high as their younger, volcanic cousins to the east, the Cascades, so I would have less of a chance of being buried under snow or losing the trail.
I hiked the majority of the wilderness last summer (approx. 34 miles over 4 days) and have wanted to come back ever since (preferably without the debilitating dehydration).