If you plan on going up the Dalton to Deadhorse, be prepared for harsh weather. I went up there second week of August of 2009, and encountered rain, below freezing temps (water bottle was frozen solid camping over night) and snow going over the Atigun Pass. TravellingStrom went up a week before me, and had a wonderful ride with sunny weather and wide views of the North Slope.
Went through Mex/CA in Oct/Nov and had both sweltering heat and torrential rains. The point being; weather conditions can change rapidly. Just prepare for varying conditions (layers and solid rain gear) and you will be alright.
2009-2010 Prudhoe Bay to Ushuaia on a red '00 Honda Transalp