This is mostly a 3 season Wilderness. Access is difficult in the winter, as snow blocks the roads to most trailheads. Also trails are not blazed for route finding in the snow. Spring is a good time to see early wildflowers, avoid the heat and insects and find adequate water on the ridge trails. But fording of early spring creeks and rivers may not be possible in early spring.
Ridge routes are often open under full sun and springs tend to dry out in later summer.
Fall can be a good time, with cooler tempertures and less insects. Remember that daylight is shorter and fall rains can cause waterways to swell quickly. Trails are only signed at trail junctions and with only the trail number. Therefore it is very important to at least have a current map with you. Also expect some small patches of snow on these trails.