After make a successful climb of Hood, here are some of the helpful websites I used in planning:

Cascade Climbers – message board for folks that just did climbs/etc
http://cascadeclimbers.com/forum/ubbthreads.php/forums/7/1/Oregon_Cascades

Mountain Forcasts.com – Best source of wind/freezing levels/temperatures by elevation for many summits:
http://www.mountain-forecast.com/peaks/Mount-Hood/forecasts/2500